Diptesh and Tushar working separately can do a piece of work in 9 days and 12 days respectively. If they work for a day alternately, Diptesh beginning in how many days the work will be completed?

Q. Diptesh and Tushar working separately can do a piece of work in 9 days and 12 days respectively. If they work for a day alternately, Diptesh beginning in how many days the work will be completed?

(A) 9

(B) 10

(C) 11

(D) 12

Answer: 11