A person can do the work in 10 days but another finishes the same work in 15 days, Together they can finish in how many days?

A) 5

B) 3

C) 6

D) 9

By using Flip rule:
So,
A’s 1 day work = 1/10
B’s 1 day work = 1/15

(A+B)’s 1 day work =

(1/10+1/15)= (3 + 2)/30 = 5/30= 1/6 

So together they can complete work in 6 days.

 

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