Donna is a mountain biking enthusiast. One Saturday, she spent the morning bikin

游客2024-01-14  16

问题 Donna is a mountain biking enthusiast. One Saturday, she spent the morning biking up an uphill trail at an average speed of 20 kilometers per hour, and then returned by the same route in the afternoon at an average speed of 25 kilometers per hour. If the downhill trip in the afternoon took 3/4 of an hour less than the uphill trek in the morning, how many kilometers did Donna ride each way?

选项 A、50
B、55
C、65
D、70
E、75

答案 E

解析 If x is the one-way distance in kilometers, then Donna’s time on the downhill ride can be expressed in hours as x/25. From the information in the question, you can form the equation ; you can restate the equation as 25x-375=20x, so 5x=375, and x=75 kilometers.
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