MPM 2D- Chapter 1 Linear Systems Word Problems Break Even Point Modeling Linear Equations Sometimes, the y = mx + b types of problems involve “break even points” (the POI) The break even point in business represents the exact moment when money spent = money earned (zero profit) (or how many things do I have to sell to cover off my spending costs) the y represents Money Earned or Money Spent the x represents the number of things sold or bought One equation represents: money spent = initial amount of money spent (b) plus a per item cost (mx) The other equation represents: money earned =per item selling price (mx) (what happened to the “b”? It’s zero!) Let’s try to model the following break even situation: You are starting a business that sells designer doggie sunglasses. Your startup costs for the business are $4800 (buy a computer, design a website, conduct research, get a celebrity canine to endorse your product). It also costs $40 to manufacture each pair of glasses. If you sell the sunglasses for $100 each, how many must you sell to break even?