※ 引述《a2515125 (Bobshih)》之銘言：
: 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
: 請問這題如何列公式？
速 x 1.25x
距 y 40-y
|---------------|----------|
全長40mile
y/x + (40-y)/1.25x
--------------------
40/x
條件一代入x=48，y未知數無法解
條件二代入y=20，分子分母x可以消去，就知道兩者的比值了。
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