To find the inverse of a function, switch the x's and y's, then solve for y again.
y = 2/3x - 17
SWITCH
x = 2/3y - 17
2/3y = x + 17
y = 3(x + 17) / 2
y = x - 10
SWITCH
x = y - 10
y = x + 10
y = cuberoot(2x)
SWITCH
x = cuberoot(2y)
x^3 = 2y
y = x^3 / 2
y = x/5
SWITCH
x = y/5
y = 5x
Hope this helps!