Efficiency Questions

To do a certain work, A is 40% more efficient than B. Working together, they can do the same work in 15 days. A started the work and left after 15 days. B and C together completed the remaining work in next 10 days. C alone can do one-third of the original work in:

A does $60\%$ of a work in 15 days. He then calls B, and they together finish the remaining work in 5 days. How long B alone would take to do the whole work?

A is 40% more efficient than B. If B alone can complete a work in 42 days, then A alone can complete the same work in how many days?

The ratio of efficiencies of $A$ and $B$ for doing a certain work is $5:8$. Working together they can complete the work in $20$ days. $A$ alone will complete $25\%$ of that work in:

A can do a certain work in 40 days. B is 60% more efficient than A. Both work together for 10 days. C alone completes the remaining work in 10
2
1
​
days. Working together, B and C can complete 44% of the original work in:

$P$ and $Q$ can do a project in $150$ and $100$ days respectively. In how many days can they complete $60\%$ of the project if they work together?