Q: 24 gallons per second of water flows down a waterfall. If you have an empty basin that can hold 260 gallons of water. The basin leaks water at 4 gallons per second. how long would it take to fill the basin with water from the waterfall in seconds?
A: 24 gallons in minus 4 gallons out is 24 - 4 = 20 gallons per second. 260 gallons divided by 20 gallons per second 260 / 20 = 13 seconds. The answer is 13.

Q: Rebecca bought 2 pies for the holiday weekend. Each pie was sliced into 8 slices. Rebecca ate 1 slice of each pie. Her family and friends ate 50% of the remaining pies over the weekend. On Sunday evening Rebecca and her husband each had another slice of pie. How many slices are remaining?
A: She bought 2 pies that had 8 slices each for a total of 2 * 8 = 16 slices. Rebecca ate 2 of the 16 slices leaving 16 - 2 = 14 slices. Her family and friends at 50% of the pie so they ate 14 * .50 = 7 slices. There were 14 slices and her family and friends ate 7 slices so that leaves 14 - 7 = 7 slices. Sunday night Rebecca and her husband each had a slice from the remaining slices so that leaves 7 - 2 = 5 slices. The answer is 5.

Q: Mrs. Choi purchased a house for $80000. Five years later, she sold it for a 20% profit and got a 5% broker's commission from the original price. How much did the house sell for?
A:
The 20% profit amounts to $80 000 x 20 / 100 = $16 000. The 5% commission amounts to $80 000 x 5 / 100 = $4 000. So the selling price is $80 000 + $16 000 + $4 000 = $100 000. The answer is 100000.