SOLUTION: Solve for X and Y X + Y=7 , X + 2Y = 11

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Question 236779: Solve for X and Y
X + Y=7 , X + 2Y = 11
Answer by College Student(505) About Me  (Show Source):
You can put this solution on YOUR website!
To solve by substitution:
1. Leave first equation alone for now.
2. Solve for y on the second equation.
3. Plug in this value into the first eqn to find x
4. Once you know the x value, plug it again in the forst equation to find y.
.
Problem:
x%2By=7
x%2B2y=11
so...
2y=11-x
y=%2811-x%29%2F2
now plug into first eqn...
x%2B%28%2811-x%29%2F2%29=7
Multiply entire eqn by 2 to eliminate the fraction.
2%2Ax%2B2%2A%28%2811-x%29%2F2%29=2%2A7
2x%2B%2811-x%29=14
Now combine like terms to solve for x
2x-x=14-11
x=3
Now plug this value in the first equation to solve for y.
x%2By=7
3%2By=7
y=7-3
y=4