Please help with this math problem

How can you solve an equation with a variable on both sides? complete the explanation. you can solve the equation by using *(blank)* operations to get the variable terms on one side of the equal sign and the constant terms on the *(blank)* side. then *(blank)* both sides by the coefficient of the resulting variable term.

How do you answer this question? (step by step)

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