P can do a work in the same time in which Q and R together can do it. If P and Q work together, the work can be completed in 10 days. R alone needs 30 days to complete the same work. then Q alone can do it in Choose the correct option.
A) 10  B) 22  C) 25  D) 27  E) 30

Rationale: work done by p and q in 1 day = 1 / 10 work done by r in 1 day = 1 / 30 work done by p , q and r in 1 day = 1 / 10 + 1 / 30 = 4 / 30 but work done by p in 1 day = work done by q and r in 1 day . hence the above equation can be written as work done by p in 1 day ã — 2 = 4 / 30 = > work done by p in 1 day = 4 / 60 = > work done by q and r in 1 day = 4 / 60 hence work done by q in 1 day = 4 / 60 â € “ 1 / 30 = 2 / 60 = 1 / 30 so q alone can do the work in 30 days answer is e .
Answer: E