Inverse function of f (x) = - 4x+12

To get the inverse, you just swap your x and y variables:

y = - 4x + 12

swap x and y, then solve for y

x = - 4y + 12 ... subtract 12

x - 12 = - 4y ... divide by - 4

(x - 12) / 4 = y

so your inverse function is (x - 12) over 4