女人梦见下雪什么意思:英文数学题解答（答案：A: 11mi/hr B: 3 mi/hr)

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A is riding a bicycle along a road and B is walking along the same road. They are 2.8 miles apart, and will be together in 12 minutes if they are travelling in opposite directions; in 21 minutes if they are travelling in the same direction. What are their respective rates?

solution:
suppose x is the rate of A,y is the rate of B
then
12/60*（x+y）=2.8
21/60*（x-y）=2.8
we have x:11 y:3

AB相距2.8英里，相向而行12分钟相遇，同向21分钟相遇。问他俩的速度。

解：设Va,Vb为A，B速度
（Va＋Vb）12／60＝2.8
（Va－Vb）21／60＝2.8
解得：Va=11,Vb=3

(a+b)*12/60=2.8
(a-b)*21/60=2.8
a=11mile/h, b=3mile/h

A'rates is 11 miles/hour
B'rates is 3 miles/hour

英文数学题解答
悬赏分：5 - 离问题结束还有 14 天 23 小时
A is riding a bicycle along a road and B is walking along the same road. They are 2.8 miles apart, and will be together in 12 minutes if they are travelling in opposite directions; in 21 minutes if they are travelling in the same direction. What are their respective rates?
答案：A: 11mi/hr B: 3 mi/hr

b

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