A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?	Choose the most appropriate option.
A) 16 B) 14 C) 15 D) 18 E) 13
A's 2 day's work= (1/20)*2=1/10   (A + B + C)'s 1 day's work =(1/20+1/30+1/60) = 6/60 =1/10   Work done in 3 days = (1/10+1/10) = 1/5   Now,	1/5 work is done in 3 days.   Whole work will be done in (3 x 5) = 15 days.   ANSWER:15
<result>C</result>
A, B and C can do a piece of work in 20, 30 and 60 days respectively. In how many days can A do the work if he is assisted by B and C on every third day?