Lisa is taking two classes a local community college. She sets aside 21 hours for homework a week with these two classes. The two classes are 4 hours each twice a week on Tuesday and Thursday. She wants to get a part-time job and ensure 8 hours of sleep each night. There are 168 hours in one week. How many hours can she work at most each week? Write and solve an inequality to determine the maximum amount of time she can work each week.

Answer 1

Lisa has 168-21 = <<168-21=147>>147 hours left in a week.
The two classes take 4*2 = <<4*2=8>>8 hours.
Lisa sleeps 8*7 = <<8*7=56>>56 hours in a week.
So, she has 147-8-56 = <<147-8-56=83>>83 hours left to work, sleep or do anything else.
Therefore, Lisa can work at most 83 hours each week. Answer: \boxed{83}.