Raju can do a piece of work in 20 days, while Ram can do it in 30 days. If both of them work at it. together, then the number of days in which they will be able to finish the work is

Explanation

Let total work is L.C.M. (20,30) = 60 units 60 Raju alone can complete the work in 20 days, => Raju's efficiency = 20 = 3 units/day 60 Similarly Ram's efficiency = 30 = 2 units/day Now, (Raju+Ram)'s 1 day's work = 3 + 2 = 5 units/day 60 ∴ Days required by Raju and Ram together to complete the work = 5 = 12 days