Question

himanshu and Abhishek can paint their house in 10 days .Abhishek and Rahul can paint their house in 15 days .Rahul and himanshu can paint their house in. 20 days . in how many days can himanshu paint the house​

Answer 1

Let us consider Himanshu as H, Abhishek as A and Rahul as R.

So,

H+A = 10 ...(i)

A+R = 15 ...(ii)

R+H = 20 ...(iii)

∵ according to the above three equations,

H = 10-A

and, R= 15-A

∴ R+H = 15-A + (10-A)

=> 20 = 25-2A

=> 2A = 25-20  (switching sides to avoid negative integers)

=> 2A = 5

=> A = 2.5

So, putting the value of A in Equation 1,

H+A = 10

=> H + 2.5 = 10

=> H = 10-2.5

=> H = 7.5

Hence, Himanshu can paint the house in 7.5 days (7 and a half days).