Allen ordered five boxes of pizza, which cost $7 each box. He then gave a tip which amounts to 1/7 of the total cost of his order. If he gave the delivery man $100, how much change did he receive? Let's answer step by step:
The total cost of five boxes of pizza is $7 x 5 = $35. He gave $35 x 1 / 7 = $5 tip to the delivery man. He spent a total of $35 + $5 = $40 for the pizza and the tip. The change that he received is $100 - $40 = $60. The answer: 60.