Question: Nelly wants to buy pizza for herself and her 14 friends. Each pizza costs $12 and can feed 3 people. If Nelly earns $4 a night babysitting the neighbors' kids, how many nights will she have to babysit to afford the pizza?
Answer: Step-by-step reasoning process: She needs to buy 15 / 3 = 5 pizzas. The pizzas cost 5 * $12 = $60 total. It will take her $60 / $4 = 15 nights worth of babysitting to afford the pizza.
So the answer is 15.

Question: 4 students participated in a 200m race. If the average completion time of the last three students was 35 seconds, and the average completion time of all four runners was 30 seconds, how long (in seconds) did it take the student who came first to finish the race?
Answer: Step-by-step reasoning process: The last 3 students had an average completion time of 35 seconds so the sum of their completion times was 3 * 35 = 105 seconds. All 4 students (now including the student who came first) had an average completion time of 30 seconds, meaning the sum of their completion times is 4 * 30 = 120 seconds. The student who came first spent 120 - 105 = 15 seconds in the race.
So the answer is 15.

Question: Tom invites his parents and 3 siblings to his house. They each eat 3 times a day. How many plates do Tom and his guests use while they are there for the 4 days if each person uses 2 plates per meal?
Answer: Step-by-step reasoning process: There were 1 + 2 + 3 = 6 people at the house. That means they use 6 * 2 = 12 plates per meal. So they use 12 * 3 = 36 plates per day. That means they use 36 * 4 = 144 plates for the visit.
So the answer is 144.

Question: Mel is three years younger than Katherine. When Katherine is two dozen years old, how old will Mel be in years?
Answer:
Step-by-step reasoning process: When Katherine is 2 dozen years old, she will be 2 * 12 = 24 years old. If Mel is three years younger than Katherine, then when Katherine is 24 years old, Mel will be 24 - 3 = 21 years old.
So the answer is 21.