18 men can complete a certain work in 15 days working 8 hours a day. How many men can complete the same work in 12 days working 9 hours a day?

Pipes A and B can fill a tank in 16 hours and 24 hours, respectively, and pipe C alone can empty the full tank in x hours. All the pipes were opened together at 10:30 AM, but C was closed at 2:30 PM. If the tank was full at 8:30 PM on the same day, then what is the value of x?

Working together, A, B and C can finish a piece of work in 3 hours. A finishes the same work in 8 hours and B finishes it in 6 hours. How long will it take for C alone to finish the same work?

Sixteen men can finish a work in 8 days. Eight men and nine women working together can finish the same work in 10 days. In how many days will twenty women finish the same work?

A is twice as good a workman as B and together they finish a piece of work in 13 days. In how many days will B alone finish the work?