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? Give the rationale and then the answer.
Let's think step by step. 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.. The answer is: 15.

Jeff has 16 GB of storage on his phone. He is already using 4 GB. If a song takes up about 30MB of storage, how many songs can Jeff store on his phone? (There are 1000 MB in a GB). Give the rationale and then the answer.
Let's think step by step. Jeff has 16 - 4 = 12GB left over on his phone. Therefore, he has 12 * 1000 = 12,000MB. Therefore, he can store 12,000 / 30 = 400 songs.. The answer is: 400.

James takes up dancing for fitness. He loses twice as many calories per hour as he did when he was walking. He dances twice a day for .5 hours each time and he does this 4 times a week. He burned 300 calories an hour walking. How many calories does he lose a week from dancing? Give the rationale and then the answer.
Let's think step by step. He burns 2 * 300 = 600 calories an hour. He dances for .5 * 2 = 1 hour per day. So he burns 600 * 1 = 600 calories per day. So he burns 600 * 4 = 2400 calories per week.. The answer is: 2400.