P and Q completed a work together and were paid ₹1,080 and ₹1,440, respectively. If P can do the entire work in 20 days, how many days did they take to complete the work together?

A can do a work in \( 7 \frac{1}{2} \) hours and B can do the same work in \( 10 \frac{1}{2} \) hours. If they work together for \(3 \frac{1}{2}\) hours, then what part of the work will be left out?

A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is:

40 persons take 6 days to complete a certain task, working 10 hours a day. How many hours a day will be sufficient for 30 persons to complete the same task in 10 days?