Question 478791
let Mary's speed = x kph
Nancy's speed = 80 kph

They reached at the same time

220/80 -220/x =1/4

LCD = 80x

(220x-220*80)/80x=1/4
220x-17600=80x/4
(220x-17600)=20x
220x-20x=17600
200x= 17600
x=17600/200
x=88 kph Mary's speed


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