4x-8y=16 on the y=mx+b?

8y = 4x - 16

<=>

y = 1/2 * x - 2

m = 1/2 = 0.5 and b = -2

4x - 8y = 16
8y = 4x - 16
y = (4x - 16)/8
y = 4x/8 - 16/8
y = 1/2(x) - 2

[m = 1/2 (0.5) , b = -2]

4x = 16 + 8y
4x - 16 = 8y
divide equaion by 8
y = 0.5x -2

Are you suppused to convert the equation from standard form into slope-intercept form?

If so, you need to solve it for y, so start with moving all y's to one side of the equation, and all others to the other, then divide by the coefficient of y to solve for it:

4x - 8y = 16
-8y = -4x + 16
y = (1/2)x - 2