一道英文数学提!janet is three times as old as her daughter,mary.five years ago jant was four times
问题描述：
一道英文数学提!janet is three times as old as her daughter,mary.five years ago jant was four times
janet is three times as old as her daughter,mary.five years ago jant was four times as old as mary .how old is janet now?how old will mary be in 7 years'time
答
Suppose Mary is x years old now.Then
4*(x-5) = 3x-5
Solve it,get x = 15
So Janet is 3x = 45 years old now and Mary will be 22 years old in 7 years' time.