Question

a can do a work in 14 days which B can do in 21 days they begin together but three days before the completion of work a leaves of the total number of days to complete the work is​

Answer 1

A’s one day work =1/14

B’s one day work=1/21

(A+B)’s one day work =1/14+1/21=(3+2)/42 =5/42

(A+B) can do the work in =42/5 =8.4 days

They work together in =(8.4–3)= 5.4days

Work done by both in 5.4 days =(5/42)×5.4

=5×54/42×10= 9/7×2= 9/14 work.

Remaining work =1- 9/14=5/14.

1 work B can do in = 21 days

5/14 work B can do in =21×5/14 =15/2=7.5 days

Total days to complete the work=5.4+7.5

=12.9 days or 13 days. Answer.