If the sum of a number and seven is doubled, the result is five less than the number

Which equation represents the partial sum of the geometric series?

What is the factored form of the following expressions? d^2 – 13d + 36

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