Let us start first writing the equation separately:
Equation 1: x+y=8
Equation 2: x+7y=8
Let us subtract Equation 1 from Equation 2
x+y=8
-(x+7y)=8
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0 -6y=0
6y=0
y=0
Now we have y=0, let us put this in any of the equation 1 or equation 2
Let us first put it in Equation 1
x+y=8
x+0=8---putting y value as y=0
x=8
Now Equation 2:
x+7y=8
x+7(0)=8
x+0=8
x=8
