The amount of money that they still have to earn in order to achieve their goal is the difference between $750 (goal) and $182.90 (current earnings) which is equal to $567.1. To determine the number of pizzas that still have to be sold, we divide this amount by the unit price of pizza.
n = $567.1 / $5.35 = 106
Therefore, Mrs. Canales' class should be able to sell another 106 pizzas.