A group of hikers is planning a trip that will take them up a mountain using one route and back down using another route. They plan to travel down the mountain at a rate of one and a half times the rate they will use on the way up, but the time each route will take is the same. If they will go up the mountain at a rate of 8 miles per day and it will take them two days, how many miles long is the route down the mountain?  Choose the correct choice from the following answers.
A) 18  B) 20  C) 22  D) 24  E) 25

Rationale: on the way down , the rate is 1.5 * 8 = 12 miles per day . the distance of the route down the mountain is 2 * 12 = 24 miles . the answer is d .
Answer: D