Answer: x-2y = -16
Work Shown:
y = (1/2)x+8
2y = 2*( (1/2)x+8 )
2y = x + 16
2y - 16= x
-16= x-2y
x-2y = -16
Side note: I multiplied both sides by 2 in the second step to clear out the fraction.
The answer x-2y = -16 is in standard form Ax+By = C
A = 1, B = -2, C = -16