Can some one explain me

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

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?

X² + 4y² = 36 the major axis runs along: a) y=4x b) x-axis c) y-axis