To find the number of pizzas Matt can buy while still being able to afford a cake set up an inequality. The inequality should look like where x is the number of pizzas Matt bought. Then, solve the inequality by first subtracting 18 from both sides, . Next, divide both sides by 12, . This means that Matt can buy 5 pizzas. At first, it might seem like you should round up; however, if you rounded up at all then Matt could not afford the cake, so you must round down.