Hey CPhill, thanks for the help!

I still have one question based on your work : )

Here is the work:

[ f-1(a) - f-1(b) ] / [a - b] = **( [ (3/2)(a + 5] - (3/2)(b) + 5] / [ a - b] =**

**[ (3/2) (a - b) ] / [ a - b ]** = 3/2

I don't understand the bolded out part, as in how you went from **[ (3/2)(a + 5] - (3/2)(b) + 5] / [ a - b] **to the next part..

Could you please further explain your steps, I am a little confused about that