What is the rate of change of y with respect to x for this function?

Which of the following would be a good name for the function that takes the weight of a box and returns the energy needed to lift it?

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

Type the correct answer in each box. spell all the words correctly, and use numerals instead of words for numbers. if necessary, use / for the fraction bar(s).