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

Tutors Answer Your Questions about Expressions-with-variables (FREE)

Question 29226: use substitution to solve the system.
y=x-3
4x+y=1
Click here to see answer by Nate(3500)

Question 29209: Determine whether the following is an expression.
m – • z

Click here to see answer by Nate(3500)

Question 29272: Please, I have tried this one several times. Solve the equation . I began by multiplying both sides by 4 over 1, is this where I should have started? Thank You, Bugee62
Click here to see answer by atif.muhammad(135)

Question 29274: A real tricky one for me. The question reads...The lengths of the sides of a quadralateral are consecutive even integers. Twice the length of the shortest side plus the length of the longest side is 120 inches. Find the lengths of the four sides. I began with 2x + y =120 and I know that this is only to figure two of the sides. I'm unsure of where to begin from here. thanks for your help.
Click here to see answer by atif.muhammad(135)

Question 29338: The speed of a boat in still water is 16 mph. The boat traveled the same distance downstream in 9 minutes that it traveled upstream in 15 minutes. Find the speed of the current....HELP!
Click here to see answer by josmiceli(9661)

Question 29264: 10x+4y=2
8x+3y=1
Click here to see answer by elima(1433)

Question 29374: Given the cost function, C(x), and the revenue function, R(x), find the number of units x that must be sold to break even?
C(x)=9000x + 45,000
R(x)=12,000x
Click here to see answer by Nate(3500)

Question 29282: a
_ = 0
8
I don't understand this question.
Click here to see answer by Bb(19)

Question 29485: I am having problems with these equations by subtitution.
8y=15-4x
x+2y=4

Click here to see answer by josmiceli(9661)

Question 29485: I am having problems with these equations by subtitution.
8y=15-4x
x+2y=4

Click here to see answer by Earlsdon(6287)

Question 29576: You are all so helpful, did not think I'd be back so soon. However I'm stuck on this one. The story problems always get me.
In triangle ABC, the measure of angle B is 2 times the measure of angle A. the measure of angle C is five degrees less than angle B. Find the measure of each angle.
All I could get was B=2A, C=B-5degrees. Do not know where to go from there, not sure how to write the equation to find B. Help Please
Click here to see answer by sdmmadam@yahoo.com(530)

Question 29547: x+y=1
2x-y=2
rules say to use substitution to solve the system
Click here to see answer by sdmmadam@yahoo.com(530)

Question 29592: 3 more than twice a number is 18
Click here to see answer by sdmmadam@yahoo.com(530)

Question 29657: can you explain how to work solvingequations with variables on both sides
Click here to see answer by ikdeep(226)

Question 29682: sum of two numbers is 42 and their difference is 30. find each of the numbers.
Click here to see answer by ikdeep(226)

Question 29765: Hello, I need help tonight...tried this problem at least 6 times. help
The difference of two numbers is 12. Two fifths of the greater number is 6 more than one third of the lesser number. Find both numbers.
I know x-y=12 and 2/5x,1/3y-6, and don't know where to go from there. Please Help.
Click here to see answer by Paul(988)

Question 29767: Right to it. I'm confused. I figured out oneproblem like this, this one I do not get.
According to the AVMA, in 1987, 34.7 million households owned a dog, and 27.7 million households owned a cat. Since 1987, dog ownership has decreased by 0.025 million households per year, and cat ownership has increased by about 0.375 million households per year. If the trend continues, after how many years will the number of households that own dogs and cats be equal?
34.7 - 0.025 and 27.7 + 0.375 how do I calculate this?
thank you
Click here to see answer by kev82(148)

Question 29811: what is trapezium
Click here to see answer by Earlsdon(6287)

Question 28386: {3x+y=5
{2x-y=10
Can you please show all work.
Click here to see answer by jb007mi6(53)

Question 29896: I need help finding the point of intersection for 6x-2y=10, and 3x-5=y.
Click here to see answer by Cintchr(481)

Question 30156: 290,251.40 = .37x

Click here to see answer by amby_2006(1)

Question 30109: 2(a-4)+4=5(9-a)
19-3n=-2n
1/2b-1/2=1/4b
0.6(x-50)=18-0.3(40-10x)
Click here to see answer by checkley71(8403)

Question 30219: x+y-2z=-1
2x-y+z=-6
3x+2y-3z=-3
Click here to see answer by Fermat(127)

Question 30318: what is r in the following equation:
12(4r-5r/6) + 20 = 19r - 15 + 45r/2 and how do you solve this?
Click here to see answer by Cintchr(481)

Question 30399: The problem says simplify the expression
(-4)(-x)(x2)
Click here to see answer by raiderluvr4ever(2)

Question 30434: how do I solve this problem?
6x-2x+11=-5

Click here to see answer by checkley71(8403)

Question 30398: 5(2x+3)+(x+1)
Click here to see answer by checkley71(8403)

Question 30452: Define variables and write a system of equations for each situation. Solve by using substitution.
Suppose you want to join a video store. Big Video offers a special discount card that costs $9.99 for one year. With the discount card, each video rental costs $2.49. A discount card from Main Street Video cost $20.49 for one year. With the Main Street Video discout card, each video rental costs $1.79. After how many video rentals is the cost the same?
Click here to see answer by mbarugel(146)

Question 30451: Solve each system by substitution. Check you solution
0.5x + 0.25y = 36
y + 18 = 16x
Click here to see answer by mukhopadhyay(490)

Question 30478: how whould I solve the equations 6x-2y=10 and x-2y= negtive 5 by using the subtution method?
Click here to see answer by sdmmadam@yahoo.com(530)

Question 30522: you have 28 coins, they are nickles and dimes. The value of the coins is $2.05
Define the variables, Write a system of equations for the solutions
Click here to see answer by checkley71(8403)

Question 29297: solve each system using the substitution method. y-2x=-6,2y-x=5
next problem. 3a+2b=2,-2a+b=8
Click here to see answer by sdmmadam@yahoo.com(530)

Question 30599: how do you solve sytems of equations by graphing? here is an example that my math book gives me: y=2x+4 I have so much trouble tryng to solve these.
x+y=-2.
I also have trouble tyring to use substitution to solve problems such as this:
y=2x-3 Please help me my math grade is going down drastically!!!!!!!
y=0

Click here to see answer by Cintchr(481)

Question 30611: Find the constant term that should be added to make the following expression a perfect square trinomial.
x^2 + 3x

answer choice of 9, 9/4, 9/2 or 3/2
my answere is 9/2 but am not confident it is correct
Click here to see answer by Earlsdon(6287)

Question 30610: Find the constant term that should be added to make the following expression a perfect square trinomial.
x^2 + 3x

answer choice of 9, 9/4, 9/2 or 3/2
my answer is 9/2 but am not confident it is correct
Click here to see answer by Nate(3500)

Question 30609: Find the constant term that should be added to make the following expression a perfect square trinomial.
x^2 + 3x

answer choice of 9, 9/4, 9/2 or 3/2
my answer is 9/2 but am not confident it is correct
Click here to see answer by venugopalramana(3286)

Question 30680: How would I go about solving this formula for the specified variable?
I = E/R for E

Click here to see answer by checkley71(8403)

Question 30681: How would I solve this forumla for the specified variable?
S=P+Prt for r
Click here to see answer by checkley71(8403)

Question 30699: Two planes leave at the same time and head in opposite directions. One travels 80mph faster than the other. After 3 hours, they are 2,940 miles apart. What is the rate of each plane? Plane one = b + 80 and plane two = b. The rest of this is not calculating for me. I know that the three hours figure in there somehow yet can't figure where. Please help me. Thanks
Click here to see answer by Paul(988)

Question 30696: Anne wants to create a mix of two coffees, one is $8.40 a lb. and the other is $7.28 a lb. How many pounds of the $7.28 coffess should she ad to 9 pounds of the $8.40 coffee to sell the mixture for $7.95 a pound? I had a problem like this last week, i did not get my homework back to use as a reference...please help, I'm lost after....$8.40 x 9 = $75.60.
Click here to see answer by Paul(988)

Question 30790: How do I solve for "Y" in the following equation? X/(X+Y)=Z
Click here to see answer by troyapplehelen(46)

Question 30817: Given that a triangel has a base and height of the same manner, x. If the base was increased by 5 and the height was decreased by 2, what is the area of the triangle? Write the solution in the simplest form.
Click here to see answer by Nate(3500)

Question 30841: The perimeter of a triangle is 93 centimeters. If two sides are equally long and the third side is 9 centimeters longer than the others, find the lengths of the three sides.
Click here to see answer by checkley71(8403)

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