# Questions on Algebra: Expressions involving variables, substitution answered by real tutors!

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 Algebra: Expressions involving variables, substitution Solvers Lessons Answers archive Quiz In Depth

 Question 68688: solve each system by substitution 5x - 2y = -5 y- 5x = 3 4x - 12y = 5 -x + 3y -1 Click here to see answer by rmromero(383)

 Question 68747: Solve the system by substitution. x + y = 12 y = 2x This problem has me a bit confused and need some help. Thanks. Click here to see answer by stanbon(57387)

 Question 68749: Solve the system by substitution. 3x – y = –7 x + y = –9 Help!! I am pulling my hair out! :0) I need help with substitution, I am not understanding. Can someone please help me. Thanks. Click here to see answer by stanbon(57387)

 Question 68825: Help, I am stuck. Beginning Algebra Chapter 8 Section 8.1. Solve each of the following systems by graphing. 3 x - 6 y = 9 x - 2 y = 3 The answer I keep getting is 0 = 0 3 x - 6 y = 9 3 ( 2 y + 3) - 6 y = 9 6 y + 9 - 6 y = 9 0 = 0 Click here to see answer by checkley71(8403)
 Question 68825: Help, I am stuck. Beginning Algebra Chapter 8 Section 8.1. Solve each of the following systems by graphing. 3 x - 6 y = 9 x - 2 y = 3 The answer I keep getting is 0 = 0 3 x - 6 y = 9 3 ( 2 y + 3) - 6 y = 9 6 y + 9 - 6 y = 9 0 = 0 Click here to see answer by rapaljer(4667)

 Question 68856: Use the substitution method to solve the linear system x+y=12 x+3/2y=3/2 Click here to see answer by checkley71(8403)
 Question 68856: Use the substitution method to solve the linear system x+y=12 x+3/2y=3/2 Click here to see answer by rmromero(383)

 Question 68859: The value of a certain 2 digit number is 5 times the sum of its digits. If the digits are reversed,the resulting number 9 more than the original number . Find the original number. T is supposed to represent the tens, and U is supposed to represent the unit. Help. Need to write out this equation and solve it. Spent 3 hours already!! Click here to see answer by stanbon(57387)
 Question 68859: The value of a certain 2 digit number is 5 times the sum of its digits. If the digits are reversed,the resulting number 9 more than the original number . Find the original number. T is supposed to represent the tens, and U is supposed to represent the unit. Help. Need to write out this equation and solve it. Spent 3 hours already!! Click here to see answer by rmromero(383)

 Question 68972: i have 3 questions. 1) 7 times the difference between d and 11 2) The number s divided by the sum of t and u 3) the number r added to the product of a and c thank you. Click here to see answer by ankor@dixie-net.com(15660)

 Question 69001: Pease help me get this answer for this mathe problem? I is on substition Algebra 1 x-y=10 5x-y=-6 Click here to see answer by stanbon(57387)

 Question 69073: I'm having trouble with In my steps it says first to group the terms. I think that is where I may ultimately be messing up. I've worked on it for awhile. The answers I am supposed to have when the problem is finished is: +2/3, -2/3, and 2 This pattern throws me off and I have more of them. A step by step guide would be a life saver. ~Jake Click here to see answer by Earlsdon(6287)

 Question 69210: there are 4 less than twice the amount of nickels. If the value of the coins are \$3.60, how many nickels are there? how many quarters? Click here to see answer by stanbon(57387)

 Question 69173: I don't know if this is the right section for this question: Each week copies of business magazines are delivered to three different stores that have ordered 75 copies, 100 copies and 150 copies, respectively. How many copes should be packaged together so that no package should be opened during delivery? Click here to see answer by checkley75(3666)

 Question 69347: I would like help with the following problem.... Between 1980 and 1990 the population of Columbus grew 12%. a) Fill in the blank.. If the 1980 population was P, then the 1990 population was _______ my answer is P+(P*.12) b) The 1990 Population was 632910. Write an equation and find the 1980 population ______________________________ P=______________ my equation P=632910-(P*.12) but now I'm lost Click here to see answer by jim_thompson5910(28598)

 Question 69361: it says to rewrite the expressions with positive exponents heres the problem 51) x to the -5 power Click here to see answer by stanbon(57387)

 Question 69381: Explain the steps you would follow to eliminate the variable x in each system of equations. Then solve the system. 6. 2x-y=6 3x+4y=-2 Explain the steps you would follow to eliminate the variable y in each system of equations. Then solve the system. 8. 4x+7y=6 6x+5y=20 Click here to see answer by stanbon(57387)

 Question 69334: I would like help with the following problem.... Between 1980 and 1990 the population of Columbus grew 12%. a) Fill in the blank.. If the 1980 population was P, then the 1990 population was _______ my answer is P+(P*.12) b) The 1990 Population was 632910. Write an equation and find the 1980 population ______________________________ P=______________ my equation P=632910-(P*.12) but now I'm lost Click here to see answer by stanbon(57387)

 Question 69618: The cd's at a store were on sale for \$10 and \$12. THE counter at the exit says 500 people left with a cd (limit 1 per customer) and the register contains \$5750. Maria wrote a system of equations for the number of \$10 and \$12 CD's. What was the system of equations. Click here to see answer by checkley75(3666)

 Question 69722: Find the rate of two cars traveling in the same direction if they leave the same place at the same. The rate of one is twice as fast as the other, and after 4 hours the faster car is 80 miles ahead of the slower car. Formula for solving motion problems is rt=d Click here to see answer by josmiceli(9697)

 Question 69762: Ok, looked in a few places but could not find it. Trying to help my daughter with her homework. This is exponential problem, I think, but can't figure out how to set it up. Humorville has a population of 8500 people. If one person tells 3 people a joke in 1 hour, how long will it take to tell the whole town of humorville. We tried graphing it out...in 1 hour 3 people, 2 hours 9 people. But that is too long. HELP, please. Thank you in advance Click here to see answer by checkley75(3666)

 Question 69765: 1. Ellen wishes to mix candy worth \$2.17 per pound with candy worth \$3.55 per pound to form 24 pounds of a mixture worth \$3.09 per pound. How many pounds of the more expensive candy should she use? 2. A cruise boat travels 84 miles downsteam in 3 hours and returns to its starting point upstream in 6 hours. Find the speed of the stream. I can't figure out the equations for either one of these word problems!! Click here to see answer by stanbon(57387)

 Question 69915: I am confused on how to solve systems using equations. here is the problem: x-2y=-8 y= -x - 2 so far i have tried this: x+-2y=-8 -2 -2 x=8-2y 2y=-8 +2 i am confused on what i am doing wrong. can you help? thanks. Click here to see answer by jim_thompson5910(28598)
 Question 69915: I am confused on how to solve systems using equations. here is the problem: x-2y=-8 y= -x - 2 so far i have tried this: x+-2y=-8 -2 -2 x=8-2y 2y=-8 +2 i am confused on what i am doing wrong. can you help? thanks. Click here to see answer by ptaylor(2048)

 Question 70014: I have the following equation: X = -((1 + Y)/W) + 1 I am trying to isolate and solve this for W. Thanks Click here to see answer by stanbon(57387)

 Question 68755: I need help in solving this equation -7x+4x=9 Click here to see answer by jim_thompson5910(28598)

 Question 70104: solve by completing the square to obtain exact solutions? x square -3x = 18 x2-3x=18 Click here to see answer by stanbon(57387)

 Question 70239: Given f(x) = 5x2 – 3x + 1, find f(–2) thanks Click here to see answer by jim_thompson5910(28598)

 Question 70243: Adult tickets for a play cost \$11 and child tickets cost \$10. If there were 23 people at a performance and the theater collected \$246 from ticket sales, how many children attended the play? thanks Click here to see answer by jim_thompson5910(28598)

 Question 70251: Determine which two equations represent perpendicular lines. (a) y = x – 3 (b) y = 3x – (c) y = x + (d) y = x – Click here to see answer by jim_thompson5910(28598)

 Question 70249: Determine which two equations represent parallel lines. (a) y = x + 4 (b) y = x – 7 (c) y = 2x + 8 (d) y = 2x – 4 Click here to see answer by jim_thompson5910(28598)

 Question 70248: Solve the system by addition. ``` –5x + 2y = 10 x – 3y = 11 Click here to see answer by jim_thompson5910(28598)  ```

 Question 70245: One number is 12 more than another. The sum of the smaller number and twice the larger number is 39. Find the larger number. Click here to see answer by jim_thompson5910(28598)

 Question 70250: Find the y-intercept. –x + 3y = 15 Click here to see answer by jim_thompson5910(28598)

 Question 70247: Sally bought three chocolate bars and a pack of gum and paid \$1.75. Jake bought two chocolate bars and four packs of gum and paid \$2.00. Find the cost of a chocolate bar and the cost of a pack of gum. Click here to see answer by checkley75(3666)

 Question 70244: Bob invested \$20,000, part at 14% and part at 13%. If the total interest at the end of the year is \$2,720, how much did he invest at 14%? thanks Click here to see answer by checkley75(3666)

 Question 70242: Rewrite the equation 2x – 3y = –6 as a function of x thanks Click here to see answer by checkley75(3666)

 Question 70241: One day, the temperature at 8:00 A.M. was 41°F, and by 1:00 P.M. the temperature was 61°F. What was the hourly rate of temperature change? Click here to see answer by checkley75(3666)

 Question 70240: Find the slope and y-intercept. x = –8 Click here to see answer by checkley75(3666)

 Question 70302: I don't get how to solve this: John flies from atlant, GA to San Fransisco, CA. It takes 5.6 hours to travel 2100 miles against the wind. At the same time, debbie flies from San Fransisco to Atlanta. Her plane travels with the same average airspeed but, with the tailwind, her flight takes only 4.8 hours. A). Write a system of equations that time, air speed, and wind speed to distance for each traveler. B). Solve the system to find the air speed. C). Find the wind speed. If you could show me how to set up these equations, that would be great because i have a few of these and the paper is due tomorrow! thanks, Rene' Click here to see answer by stanbon(57387)

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