Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Q: Problem: vehicle x is 22 miles ahead of vehicle y, which is traveling the same direction along the same route as vehicle x. if vehicle x is traveling at an average speed of 36 miles per hour and vehicle y is traveling at an average speed of 45 miles per hour, how long will it take vehicle y to overtake and drive 23 miles ahead of vehicle x ?
Options: a. 5 hours, b. 7 hours 20 minutes, c. 4 hours, d. 3 hours 45 minutes, e. 2 hours 30 minutes

A: a
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Q: Problem: walking at 4 / 5 of her normal speed, a worker is 10 minutes later than usual in reaching her office. the usual time ( in minutes ) taken by her to cover the distance between her home and her office is
Options: a. 30, b. 35, c. 40, d. 45, e. 50

A: c
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Q: Problem: in 1998 the profits of company n were 10 percent of revenues. in 1999, the revenues of company n fell by 20 percent, but profits were 20 percent of revenues. the profits in 1999 were what percent of the profits in 1998 ?
Options: a. 80 %, b. 160 %, c. 120 %, d. 124.2 %, e. 138 %

A:
b
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