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Question 231232: how do u solve a system by substitution x+y=14 and -7x+7y=-14
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! x + y = 14
-7x + 7y = -14
Solve for y in the first equation to get:
y = 14 - x
Substitute for y in the second equation to get:
-7x + 7 * (14-x) = -14
Solve for x.
Remove Parentheses to get:
-7x + 7*14 - 7x = -14
Combine like terms to get:
-14x + 7*14 = -14
subtract 7*14 from vboth sides to get:
-14x = -14 - 7*14
Simplify and combine like terms to get
-14x = -112
Divide both sides by -14 to get:
x = 8
Now that you have x = 8, go back to your first equation and solve for y
Your first equation is:
x + y = 14
Replace x with 8 to get:
8 + y = 14
Solve for y to get y = 6
You have:
x = 8
y = 6
Substitute in second equation to get:
-7*8 + 7*6 = -14
This becomes -56 + 42 = -14 which becomes -14 = -14 which is true.
Values of x = 8 and y = 6 are good.
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