यदि 100 पुरुष किसी कार्य को 20 दिनों में पूरा कर सकते हैं, तो उसी कार्य को 16 दिनों में पूरा करने के लिए कितने अतिरिक्त पुरुषों की आवश्यकता होगी?

If P and Q together can complete a piece of work in 15 days and P alone can do it in 45 days, in how many days can Q alone complete that work?

A can lay a railway track between two stations in 16 days and B can do the same job in 12 days. With the help of C, they finished the job in 4 days. In how many days can C alone do the job?