How do I find the inverse of this function

f(x)=3k(2x-4)

?

f(x)=3k(2x - 4)
y = 3k(2x - 4)
x = 3k(2y - 4)
x = 6ky - 12k
x - 12k = 6ky
..........x - 12k
y =--------------------
...........6k
............x - 12k
f⁻¹(x) = ------------ answer//
...............6k