Question: 48 people are riding a bus. On the first stop, 8 passengers get off, and 5 times as many people as the number who got off from the bus get into the bus. On the second stop 21, passengers get off and 3 times fewer passengers get on. How many passengers are riding the bus after the second stop?
Answer: 
At the first stop, 5 * 8 = 40 passengers get on the bus.
After the first stop the bus has ( 48 - 8 ) + 40 = 80 passengers.
At the second stop, 21 / 3 = 7 passengers get on the bus.
After the second stop there are ( 80 - 21 ) + 7 = 66 passengers.