I need help fast plsss

Its worth 10000000 points need asap if you answer correctly ill mark brainliest

If f(x)=2x-6 and g(x)=3x+9, find (f-g)(x)

Suppose you are an avid reader and are looking to save money on the cost of books instead of paying about $20 for each book, you decide to look into purchasing a kindle for $120 you can purchase e-books for about $5 each 1. find the slope-intercept equation for the cost of the hard copy of books using x to represent the number of books 2. find the slope-intercept equation for the cost of the kindle with cost of e-books using x to represent the number of books