SOLUTION: My daughter is supposed to solve this problem using substitution. I don't get it. The problem is: -7x-2y= -13 x-2y=11 Can you help me try to explain this to her?

Question 256543: My daughter is supposed to solve this problem using substitution. I don't get it. The problem is:
-7x-2y= -13
x-2y=11
Can you help me try to explain this to her?
Found 2 solutions by Alan3354, ankor@dixie-net.com:
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
-7x-2y= -13
x-2y=11 --> x = 2y+11
-------------
Sub for x into the 1st eqn
-7(2y+11) - 2y = -13
-14y-77 - 2y = -13
-16y = 64
y = -4
---------
sub for y into either eqn
x-2y=11
x-2(-4) = 11
x+8 = 11
x = 3

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
substitution. I don't get it. The problem is:
-7x - 2y = -13
x - 2y = 11
:
Choose one of the equation to use for substitution, the 2nd equation
x - 2y = 11
Add 2y to both sides
x = 2y + 11
:
Now we can substitute (2y+11) for x in the 1st equation, find y
-7x - 2y = -13
-7(2y+11) - 2y = -13
Multiply what's inside the brackets by -7
-14y - 77 - 2y = -13
add 77 to both sides
-14y - 2y = - 13 + 77
do the math
-16y = +64
The variable has to be positive, multiply both sides by -1
16y = -64
Divide both sides by 16
y =
y = -4
:
Solve for x in the 1st equation, substitute -4 for y in the 1st equation
:
-7x - 2y = -13
-7x - 2(-4) = -13
-7x + 8 = -13 Subtract from both sides
-7x = -13 - 8
-7x = -21
Multiply both sides by -1
7x = 21
x =
x = +3
:
:
Check solutions in the 2nd equaiton x-2y=11
3 - 2(-4) = 11
3 + 8 = 11; confirms our solutions
RELATED QUESTIONS
I'm trying to solve the system using substitution. I don't understand it. The problem is... (answered by ikleyn)
good evening, I am not sure if this is where I need to ask the question on solving... (answered by ankor@dixie-net.com)
I know how to solve for X and Y in linear systems of equations using SUBSTITUTION. My... (answered by htmentor)
can you help me and show me how to solve this problem you must solve system using... (answered by vleith)
Im taking algebra 1 and I don't understand at all Im stuck on this one problem I just... (answered by rfer)
Using Substitution 4x + 2y = 1 2x + 3y = .70 Solving for X in the first problem 4x... (answered by Fombitz)
how do you solve -7x-2y=-13 x-2y=11 using... (answered by stanbon)
2.how can i solve this system of equation by substitution -7x-2y=-13,x-2y=11? pls help... (answered by jim_thompson5910,tinbar)
My niece needs help. I tried to solve it but I don`t think I got it correctly. This is... (answered by scott8148,stanbon)