My question is: Andrew's father buys a package of 100 masks. Andrew lives with his 2 parents and 2 siblings. All members of Andrew's family change masks every 4 days. How many days will it take to finish the pack of masks? Your thoughts:
Andrew's family consists of 1 + 2 + 2 = 5 people. Each of Andrew's family members uses 100 masks / 5 = 20 masks. With everyone wearing a mask every 4 days, the masks will last 20 masks * 4 days / mask = 80 days. The final answer: 80.