Change it into a formula:
[tex]y = \frac{1}{4} x - 12[/tex]
Change x and y and solve for y:
[tex]x = \frac{1}{4} y - 12[/tex]
Remove the fraction by multiplying both sides by 4:
[tex]4x = y - 48[/tex]
Then solve for y:
[tex]y = 4x + 48[/tex]
The inverse is:
[tex]{f(x)}^{-1} = 4x + 48[/tex]
