A problem for Beginning Pre Calc!! Help asap?

Question

10 points to anyone who can kinda explain how you got the answer to me (just head me in the right direction). Thank you so very much.

Find the difference quotient of f, that is, find f(x+h)-f(x) /h , h doesnt = 0, for the following function.

F(x)=6x+4

f(x+h)-f(x)/h=

Answer 1

[f(x + h) - f(x)]/h = {[6(x + h) + 4]  - (6x + 4)}/h =

= (6x + 6h + 4 - 6x - 4)/h = 6h/h = 6