122. 12343-!-item-!-187;#058&008383
During a 40-mile trip, Marla traveled at an average speed of x miles per hour
for the first y miles of the trip and at an average speed of 1.25x miles per
hour for the last 40 - y miles of the trip. The time that Marla took to
travel the 40 miles was what percent of the time it would have taken her if
she had traveled at an average speed of x miles per hour for the entire trip?
(1) x = 48
(2) y = 20
答案是B
懇求詳細算法 感謝你
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