Time and Work Questions

Sashi can do a piece of work in 20 days. Tanya is 25% more efficient than Sashi. The number of days taken by Tanya to do the same piece of work is:

A can do a work in 20 days and B in 50 days. If they work on it together for 5 days, then what fraction of work is left?

X, Y and Z can do a piece of work in 30,40 and 50 days respectively. All three of them began the work together but Y left 4 days before completion of the work. In how many days was the work completed?

If 10 people can do a job in 20 days,then 20 people with twice the efficiency can do the same job in

S and T can finish a work in 50 days. They worked together for 20 days and then left. How much of the work is left?

A and B together can complete a task in 12 days. However, if A works alone, completes half the job and leaves and then B works alone and competes the rest of the work, it takes 25 days in all to complete the work. If B is more efficient than A, how many days would it have taken B to do the work by herself?

Mahanath works 2 times as fast as Sahay. If Sahay can complete a job alone in 21 days, then in how many days can they together finish the job?

20 boys do one fourth of work in 25 days. How many more boys will be required to complete the remaining work in 50 days?