Theresa is testing the lifespan of light bulbs for a school project. After testing 10 Brand A light bulbs and 10 Brand B light bulbs, she finds that Brand A bulbs last, on average, 4 hours longer than Brand B light bulbs. What inference can she make from these tests?​

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