Question

The table shows ordered pairs of the function y = 8 - 2x. When x = 8, the value of y is

Answer 1

When you substitute 8 in for the x in 8-2x. You get 8-2(8) or 8-16 which is -8. 

Answer 2

If we plug in x, we should be able to find y because then there's only 1 unknown value in the equation.
y=8-2x
y=8-2(8)
y=8-16
y=-8