RRB Junior Engineer Stage 1 Model Papers 6

According to question,
If P can complete a work in 1 day, Q can complete the same work in 4 days.
Hence, if the difference is 3 days, Q can complete the work in 4 days
⇒ If the difference is 45 days, Q can complete the work in 60 days
∴Q's 1 day's work$=\frac{1}{60}$
∴ P's 1 day's work $=4\times \frac{1}{60}=\frac{1}{15}$
∴ (P + Q)'s 1 day's work ∴ P and Q together can do work in 12 days.