Question

A,B,C can finish a job in 2 hours if A alone can finish the job in 5 hours B alone can finish the job in 6 hours how long will it take for C to finish the job alone

Answer 1

C alone can do the work =1/2-(1/5+1/6)
=1/2-11/30=4/30=2/15=1/7.5
hence in 7.5 hrs C can do the work alone
hope it's useful.