Systems of Equations - Elimination7x+8y=20 7x-y=29

First, isolate y in 7x-y=29 because 1 is y's coefficient.
7x-y=29
-y=29-7x
y=7x-29
Now, substitute 7x-29 for y in 7x+8y=20.
7x+8y=20
7x+8(7x-29)=20
7x+56x-232=20
Add all coefficients.
63x-232=20
Isolate x by adding 232 to both sides.
63x-232=20
63x=252
x=4
Now, substitute 4 for x in your first equation.
y=7x-29
y=7(4)-29
y=28-29
y=-1
Your answer would be (4,-1).
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