Question

Viral can do a piece of work in 10 days & Raja in 15days. If both of them work together how long will it take to finish the work?

Answer 1

Let us take x = Time it will take for both of them

Then,

x(1/10 + 1/15) = 1

x(15 + 10) = 150

x(25) = 150

x = 6 days 

Hope i helped you! :)

Answer 2

work can do by viral=10 days
work can do by raja=15days
efficency of viral= 1/10
efficency of raja=1/15
by adding eifficiency we can get their efficiencies
1/10+1/15= 3+2/30=5/30=1/6
 we have get teir effciency 
 so no of days = 6