25 / 1.25 = 20 days

Vinay can do a certain work in 16 days. Shubham is 60% more efficient than Vinay. How many days does Shubham alone take to do the same work?

X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?

A certain number of workers can finish a piece of work in 100 days. If there were 10 workers less, it would take 10 days more for the work to be finished. How many workers were there originally?

A certain number of men can finish a piece of work in 30 days. If however there were 15 men less it will take 30 days more for the work to be finished. How many men were there originally?