Question

Anil can do a work in 5 days and ankur in 4 days. How long will they take to do the same work if they work together?

Answer 1

anil does work in 5 days
therefore, anil's 1 day work=1/5

ankur does work in 4 days
therefore ankur's 1 day work= 1/4

therefore,
(anil+ankur)'s 1 day work=1/5 + 1/4
                                        =9/20

therefore,anil and ankur do the work together in 1/(9/20)
                                                                              =20/9

=2 days (4hrs 48 min)....