SOLUTION: solve this equation using the substitution method x+y=20 x-y=4

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Question 775421: solve this equation using the substitution method
x+y=20
x-y=4
Answer by sofiyac(983) About Me  (Show Source):
You can put this solution on YOUR website!
add y to each side of the equal sign of the second equation
a) x=4+y now plug that into the first equation
4+y+y=20
4+2y=20 subtract 4 from each side
2y=16 divide each side by 2
y=8 now plug that into equation marked with a)
x=4+8
x=12
so the solution is (12,8)