$\frac{3}{4}$ part of the tank is filled by a motor pump in 15 minutes, then the rest part of the tank will be filled in

A and B working together can finish a piece of work in 12 days while B alone can finish the same work in 30 days. Then determine that in how many days can A alone finish the same work?

Mohan asked 36 men to build his house in 30 day. 50% of the work got completed in just 10 days. So, Mohan removed some workers. Now, how many persons does he need to complete the remaining work in decided time?

A can do a certain work in 12 days. B is 60% more efficient than A. How many days does B alone take to do the same work?

A can finish a work in 16 days and B can do same work in half the time taken by A. Then, working together, what part of same work they can finish in a day ?

P completed $\frac{2}{5}$ part of certain work in 12 days. Further, Q completed the rest of the work in 18 days. In how many days could P and Q complete the work, if they worked together?

A and B together can complete a piece of work in 12 days. A alone can complete the work in 15 days. In how many days can B alone complete the same work?