Answer the following question.
Grace can read a 200-page book in 20 hours. How long would it take her to finish reading a 250-page book at this constant rate?
Step-by-step reasoning process: Grace can read 200 / 20 = 10 pages in 1 hour. So she can finish a 250 - page book in 250 / 10 = 25 hours.
The answer is 25.

Answer the following question.
A couple with two children, ages 6 and 10 years old, decided to go to an amusement park. The regular ticket costs $109, but children below 12 years old have a $5 discount. If they gave the cashier $500, how much change will they receive?
Step-by-step reasoning process: The ticket costs 109 - 5 = $104 for each child. So the ticket cost of the two children is 104 x 2 = $208. The couple needs to pay the regular price, so it's 109 x 2 = $218. Thus, the family needs to pay a total of 208 + 218 = $426. Therefore, their change is 500 - 426 = $74.
The answer is 74.

Answer the following question.
A doctor needs to give medicine to a child, and he knows that he cannot give the same amount of medicine that he would give to an adult. The instructions say that for every kilogram of weight the child must be given 5 ml of medicine. The doctor knows that the child weighs 30 kilograms and that also the full dose has to be given in 3 equal parts. How many milligrams will each part of the dose be?
Step-by-step reasoning process: The total number of ml needed is 30 kg x 5 ml / kg = 150 ml. Each dose has to be 150 ml / 3 doses = 50 ml / dose.
The answer is 50.

Answer the following question.
Aubriella is pouring water into a 50-gallon fish tank at the rate of 1 gallon every 20 seconds. How many more gallons will she have to pour into the tank to fill the tank if she poured water into the fish tank for 6 minutes?
Step-by-step reasoning process: When she poured water into the gallon for 6 minutes, the total time in seconds she took is 6 minutes * 60 seconds / minute = 360 seconds. If in 20 seconds she poured 1 gallon of water into the tank, in 360 seconds, she poured 360 seconds / 20 seconds / gallon = 18 gallons of water into the tank. Aubriella will have to pour 50 gallons - 18 gallons = 32 more gallons into the tank to fill the tank.
The answer is 32.