# 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 244044: Would you please show me how to solve the eqation for the variable indicated in this problem? X = 5y for y Thank you for your time and help! Click here to see answer by jim_thompson5910(28476)

 Question 244256: please help me solve y=2x+7 3x-y=-9 i have tried to solve it but cant get it right and i dont know what im doing wrong Click here to see answer by richwmiller(9135)

 Question 244266: How do I solve this equation for the variable indicated? I appreciate your help! 3m-7n = p for m Click here to see answer by richwmiller(9135)

 Question 244341: Solve by the substitution method. I have part of this I will add it here and hopefully someone can help me with the last part. Solve by the substitution method. 8x+2y=-46 -6x+y=47 Ok, so you start with the second equation to make it more simple. 1(-6x+47) y=-6x+47 Substitute that for y in the first equation. 8x+2(-6x+47)=-46 8x-12+94=-46 Collect like terms. -4x+94-94=-46+94 -4x=48 x=-12 Is this correct so far? So next you would take -12 and substitute it into the second equation. -6(-12)+47 72+47 y=119 So my ordered pair would be (-12,119) except I know this is wrong, I am just wondering exactly what I did wrong here. Thanks in advance. Click here to see answer by scott8148(6628)

 Question 244391: Ok, here is the next problem that I am facing. I can figure the first part, but cannot make sense of the second part. 5x+3y=-11 7x-2y=-17 2(5x+3y=-11) = 10x+6y=-33 3(7x-2y=17)= 21x-6y=51 10x+6y=-33 21x+6y=51 31x=18 x=18 31 Correct so far right? Here is what I can not figure out: I would then take X and substitute into either one of the equations. I chose the second one. 7(18/31)-2y=17 No logically, I would need to eliminate the y out of the equation somehow, but how? 7(18/31)-2y+2y=17, but then I would have to add it back on behind the 17 right? Here is what the example from Mathlab shows: So the only answer that I can derive from this is by multiplying 7(18/31) which equals 126/31, now what??? What do I do with the rest of the equation? Click here to see answer by scott8148(6628)
 Question 244391: Ok, here is the next problem that I am facing. I can figure the first part, but cannot make sense of the second part. 5x+3y=-11 7x-2y=-17 2(5x+3y=-11) = 10x+6y=-33 3(7x-2y=17)= 21x-6y=51 10x+6y=-33 21x+6y=51 31x=18 x=18 31 Correct so far right? Here is what I can not figure out: I would then take X and substitute into either one of the equations. I chose the second one. 7(18/31)-2y=17 No logically, I would need to eliminate the y out of the equation somehow, but how? 7(18/31)-2y+2y=17, but then I would have to add it back on behind the 17 right? Here is what the example from Mathlab shows: So the only answer that I can derive from this is by multiplying 7(18/31) which equals 126/31, now what??? What do I do with the rest of the equation? Click here to see answer by edjones(7569)

 Question 244482: How do I solve this equation for the variable indicated? a+3/b = c for a ( that reads a+3 all over b I do not know how to write it better -thanks!) Click here to see answer by nyc_function(2733)

 Question 244625: Identify the variable If the line that passes through (5,d) and (9,2) 1/2 the slope of -3/4 find the equation of the line associated with the point. How can I find the line associated with the point especially when I don't have a number and the number is replaced with a letter? Click here to see answer by richwmiller(9135)

 Question 244623: If the Product of a number and -3 is reduced by 5, the result is 25 less than twice the opposite of the number . find the number Click here to see answer by richwmiller(9135)

 Question 244690: Below is an algebra expression from my text that I help on how to do step by step. "The rate, given that the distance is 200 feet and the time is x + 3 seconds." Click here to see answer by richwmiller(9135)

 Question 244694: Solve by the elimination method. 5x+3y=-11 7x-2y=17 I did a solution to this one and would love to know if I did it correctly. Thanks in advance. Ok, I think I may have puzzled through it. Let me see here. I am gonna start from the very beginning but with the CORRECT signs on all of the numbers, a mistake that I made when I originally typed this question. 5x+3y=-11 7x-2y=17 2(5x)+2(3y)=2(-11) 3(7x)-3(2y=3(17) 10x+6y=-22 21x-6y=51 31x=29 x=29/31 Is this correct so far? 5(29/31)+3y=-11 145/31+3y=-11 3y=-11-145/31...am I on the right track? 31(-11)-145 -486/31 -486/3=-162 y=-162/31 Ok, hopefully this is correct. I am sorry for taking up so much of your time, and I want you to know that I REALLY appreciate you trying to help me through this. I really feel like I am a lost cause at this point though. Click here to see answer by jim_thompson5910(28476)

 Question 244786: I can't figure out how to solve for x. My problem is xc - 5 = y. I missed the day they discussed this and I'm lost. Please help - Thanks! Click here to see answer by jim_thompson5910(28476)

 Question 244847: I have to use substitution to solve the equation below & don't know where or how to begin: 3x-5y=11 x-3y=1 Click here to see answer by dabanfield(803)

 Question 244871: x/3=2/10 can u show step by step how you got the answer and thank you Click here to see answer by dabanfield(803)

 Question 244870: i need to solve using substitution. how do i go about solving this problem: 5r-s=5 -4r+5s=17 Click here to see answer by scott8148(6628)

 Question 245021: write and solve an equation for each situation. The great Seto Bridge in Japan is about 7.6mi long. How long would it take you to cross the bridge if you were walking at 4mi/h? Click here to see answer by stanbon(57219)

 Question 245053: tennis balls are sold in packages of three balls. number of balls / number of packages 30 / 10 72 / 24 378 / 126 999 / 333 t / I can't remember how to find t. I don' see a pattern. Click here to see answer by checkley77(12569)

 Question 245332: machine A can fill a gallon container in 7 minutes while machine B can fill the same container in 5 minutes. create an equation and determine how long it would take if they filled the container at the same time. Click here to see answer by dabanfield(803)

 Question 245361: the expenditure,E(t), in billions of dollars, by oil companies for new oil and natural gas projects can be approximated by the equation E(t)=7t^-7.8+82.2, where t is the number of years since 2001. A) find the expenditure of oil companies for new oil and gas projects in 2004? B)if this trend continues, in what year will the expenditure be \$579 billion? Click here to see answer by sanjay_sp008(2)

 Question 245456: Use the functin below to solve for t in terms of the other variable. A= P (1+r/n)^nt Click here to see answer by jsmallt9(3296)

 Question 245617: If Laura can type a page in p minutes, what piece or the page can she do in 5 minutes? Click here to see answer by edjones(7569)

 Question 245731: the perimeter of my bedroom is 56 feet. the length is 8 more then the width. what are the dimensions of my room? thanks. Click here to see answer by richwmiller(9135)

 Question 245867: What do you do when you have a variable on both sides Example 2g+14+5g=8g-3+8 Click here to see answer by richwmiller(9135)
 Question 245867: What do you do when you have a variable on both sides Example 2g+14+5g=8g-3+8 Click here to see answer by dabanfield(803)

 Question 245858: 6B+4=2(2B+1) I did 6b+2b is 8B 4+1is 5 multiplied by 2 is 10 Click here to see answer by richwmiller(9135)

 Question 245958: g(x) = √( x - 1) + √(2x), find all values of x for which g(x) = 6 Click here to see answer by stanbon(57219)

 Question 246143: 7x − 8 = −9x + −104 2x = 2(−16 + 5x) Click here to see answer by checkley77(12569)