30 persons can do a piece of work in 24 days. How many more people are required to complete the work in 20 days?

If 20 women can lay a road of length 100m in 10 days. 10 women can lay the same road of length 50m in: 

A and B can do a work in 18 and 24 days respectively. They worked together for 8 days and then A left. The remaining work was finished by B in 

16 boys or 12 women can do a piece of work in 28 days. In how many days will the same work be done by 4 boys and 4 women, if they all work together?

24 women take 14 days to complete a piece of work which can be completed by 14 men in 12 days. 18 men started working and after 5 days, 10 men left and 8 women joined them. How many days will it take them to complete the remaining work?

P can do a task in 30 days, Q is 50% more efficient than P, R can do the same work in 10 days less than Q if R and Q start task together and after X days they left the task and P completed the remaining task in (X + 8) days. then find the value of X?

A, B and three men can finish a work in 10, 20 and 15 days respectively, then in how many days will all three together finish the work?

Time taken to travel a certain distance of ‘x’ km at speed of 40 km/h is 2 hours more than the time taken to travel (x+20) km at speed of 60km/h. Find the time taken to travel (x+40) km at the speed of 40 km/h?