There are 10 cars parked in a mall's parking lot, each with the same number of customers inside. Each customer only makes 1 purchase. If the sports store makes 20 sales and the music store makes 30 sales, how many customers are in each of the cars? Think carefully first, then make a decision:
As each sale represents a customer, there must be a total of 20 sports store sales + 30 music store sales = 50 customers. There is an equal number of customers in every car, so there must be 50 total customers / 10 cars = 5 customers in each car. So, the answer is 5.