Question

John can finish a painting job in 2 days. Peter can finish the
job in 3 days. Danny can do the job in 6 days. How long will
it take all of them together to finish the job?

Answer 1

It follows that John can do $\frac{1}2$ part of the job per one day, Peter can do $\frac{1}3$ part of the job per one day, and Danny can do $\frac{1}6$ part of the job per one day. Taking into accounrt that $\frac{1}{2}+\frac{1}3+\frac{1}6=\frac{3+2+1}{6}=\frac{6}{6}=1,$

we conclude that it will take one day all of them together to finish the job.