Tom hasn't been sleeping well lately. He figures he has been getting about 5 hours of sleep each weeknight and 6 hours each night on the weekend. If Tom would ideally like to get 8 hours of sleep each night on both weeknights and weekends, how many hours of sleep is Tom behind on from the last week? Let's answer step by step:
Tom ideally wants to sleep 8 hours a night for 7 days, 8 x 7 = 56 hours sleep total for the week. Tom has actually only slept 5 hours each weeknight, 5 x 5 = 25 hours of sleep. Tom has only slept 6 hours each night on the weekend, 6 x 2 = 12 hours of sleep. Total, Tom has gotten 25 + 12 hours = 37 hours sleep. The difference between how many hours Tom would like to sleep, 56, and how many hours he's actually slept, 37, is 56 - 37 = 19 hours of sleep that Tom is behind on. The answer: 19.