Mr. Maxwell takes 1 hr to drive to work in the morning but 1 and half hours to drive back home in the evening. If the morning and evening traffic is similar and he drives at an average speed of 30mph in the morning, what is the average speed of his return journey? Give the rationale and then the answer.
Let's think step by step. In the morning he travels at an average speed of 30mph for 1 hour so he covers a distance of 30 * 1 = 30 miles. He covers the same distance of 30 miles in the evening spending 1.5 hours so his average speed must be 30 / 1.5 = 20mph.. The answer is: 20.

Tom opens an amusement park. It cost $100,000 to open initially. It also cost 1% of that to run per day. He sells 150 tickets a day for $10 each. How long will it take to make back his money? Give the rationale and then the answer.
Let's think step by step. It cost 100,000 * .01 = $1,000 a day to keep the place open. He makes 150 * 10 = $1500 a day from the park. So he makes a profit of 1500 - 1000 = $500 a day. So it takes 100000 / 500 = 200 days to make back his money.. The answer is: 200.

Theo can eat 13 cookies, 3 times a day, 20 days each month. How many cookies can he eat in 3 months? Give the rationale and then the answer.
Let's think step by step. The total amount of cookies he can eat in a day is 13 x 3 = 39. The total amount of cookies he can eat in a month is 39 x 20 = 780. Therefore, the total amount of cookies he can eat in 3 months is 780 x 3 = 2340.. The answer is: 2340.