-8x + y = 6
in the first equation, isolate y and then it becomes...
y = 6 + 8x
use this to replace the y in the second equation.
7x - 1y = -4
let y = 6 + 8x
7x - (6 + 8x) = -4
7x - 6 - 8x = -4
-x - 6 = -4
x + 6 = 4
x = 4 - 6
x = -2
now use this x = -2 into the equation with y.
y = 6 + 8x
y = 6 + 8(-2)
y = 6 -16
y = -10
Therefore, x = -2 and y = -10
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