List of top Quantitative Aptitude Questions on Time and Work asked in ATMA

A and B together do a work in 12 days; B alone does it in 20 days. In how many days can A alone do it?
15 men can build a wall in 8 days. How many days will 10 men take to build the same wall?
A can do a piece of work in 12 days and B in 18 days. Working together, they finish it in: