Help ya girl out? just a little bit confused, thank you!

Simplify 24÷(-2)(3)+7 a. -29 b. 3 c. 11

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

10x − 5y + 14 = 0 whats the answer pls