[Question]: John has 3 bedroom doors and two outside doors to replace. The outside doors cost $20 each to replace and the bedroom doors are half that cost. How much does he pay in total?
[Answer]: The outside doors cost 2 * $20 = $40. Each indoor door cost $20 / 2 = $10. So all the indoor doors cost $10 * 3 = $30. That means the total cost is $40 + $30 = $70.
So the answer is 70.

[Question]: The vending machine fails to drop a snack when it’s purchased one in six times. One in ten times, it will accidentally drop two snacks. The rest of the time, it drops the purchased snack. If thirty people have used the vending machine once each to purchase a snack, how many snacks has the vending machine dropped?
[Answer]: The vending machine has been used 30 times, so it has failed to drop a snack 30 / 6 = 5 times. The vending machine has dropped 2 snacks 30 / 10 = 3 times. It has operated normally and dropped 1 snack 30 - 5 - 3 = 22 times. Thus, the vending machine has dropped 22 + 3 * 2 = 22 + 6 = 28 snacks in thirty uses.
So the answer is 28.

[Question]: Billy has four horses. Each one eats 4 pounds of oats, twice a day. How many pounds of oats does he need to feed his horses for 3 days?
[Answer]:
At each feeding Billy serves 4 horses x 4 pounds of oats / horse = 16 pounds / feeding. Each day Billy uses 16 pounds of oats / feeding x 2 feedings / day = 32 pounds of oats / day. Triple that amount to find the amount of oats needed to feed the four horses for three days: 32 pounds of oats / day x 3 days = 96 pounds.
So the answer is 96.