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A50% increase followed by 33 1/2% decrease

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

Mrs. sling bought a pound of green beans for $1.80. how much will mrs. tennison pay for 3 1/2 pounds of green beans?