बीस पुरुष एक कार्य को 30 दिनों में पूरा कर सकते हैं। कितने दिनों के बाद 5 पुरुषों को कार्य छोड़ देना चाहिए ताकि पूरा कार्य कुल 35 दिनों में समाप्त हो सके?

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?