William's class set a goal each week of the number of cans of food that is to be collected. On the first day, 20 cans were collected. Then the number of cans increased by 5 each day. If they collected 5 days a week to reach their goal, how many cans of food was their goal per week? Let's answer step by step:
On the second day, they collected 20 + 5 = 25 cans. On the third day, they collected 25 + 5 = 30 cans. On the fourth day, they collected 30 + 5 = 35 cans. On the fifth day, they collected 35 + 5 = 40 cans. Thus, the goal of William's class is to collect a total of 20 + 25 + 30 + 35 + 40 = 150 cans of food per week. The answer: 150.