If 8 carpenters can make 50 chairs in 10 days, how many carpenters are needed to make 75 chairs in 10 days? Give the rationale and then the answer.
Let's think step by step. The carpenters need to produce 75 / 50 = 1.5 times as many chairs in the same number of days. It will require 1.5 times as many carpenters to produce the extra chairs, so 8 * 1.5 = 12 carpenters will be required.. The answer is: 12.

Donna worked 2 hours every morning walking dogs in her neighborhood for $10.00 an hour. 5 days a week, after school, she worked at a card shop for 2 hours and made $12.50 an hour. On the weekends, she usually made $10.00 an hour babysitting and was guaranteed 4 hours every Saturday from her neighbor. How much money did she make over 7 days? Give the rationale and then the answer.
Let's think step by step. She makes $10.00 an hour for 2 hours walking dogs so she makes 10 * 2 = $20.00 every morning. Over 7 days she makes 7 * 20 = $140.00 a week. She makes $12.50 for 2 hours working at a card shop so she makes 12.5 * 2 = $25.00. She works there 5 days a week so she makes 5 * 25 = $125.00 a week. She also babysits for 4 hours making $10.00 an hour for a total of 4 * 10 = $40.00. Over 7 days, she makes 140 + 125 + 40 = $305.00.. The answer is: 305.

A swimming pool is being emptied through a drain at the bottom of the pool and filled by a hose at the top. The drain can empty the pool in 4 hours and the hose can fill the pool in 6 hours. The pool holds 120 liters of water. If the pool starts filled with water, how much water will be left after 3 hours? Give the rationale and then the answer.
Let's think step by step. It takes the drain 4 hours to empty the pool, so it drains at a rate of 120 liters / 4 hours = 30 liters / hour. After 3 hours, the drain will have removed 3 * 30 = 90 liters of water from the pool. It takes the hose 6 hours to fill the pool, so it fills at a rate of 120 liters / 6 hours = 20 liters / hour. After 3 hours, the hose will have added 3 * 20 = 60 liters of water to the pool. After 3 hours, there will be 120 liters + 60 liters – 90 liters = 90 liters of water left in the pool.. The answer is: 90.