If Priya and Renu can do a job in 12 hours (working together at their respective constant speeds) and Priya can do the job alone in 18 hours, in how many hours can Renu do the job alone?

36

Priya + Renu = 12 hours,

Priya = 18 hours,

⇒ Priya + Renu = 3    (Efficiency)

⇒ 2 + Renu = 3

⇒ Renu = 1,

Therefore, time required for Renu to complete the total work alone = \(\frac{36}{1}\) = 36 hours,    ..(\(\frac{Work}{Efficiency}\) = Time)