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 correct choice from the following:
A) 12	B) 15	C) 16	D) 18	E) 19
one day work done by A=1/20   work done by A in 2 days=1/10   work done by A,15,C on 3rd day=1/10+1/10=1/5   1/5th of the work will be completed at the end of 3 days   the remaining work =1-1/5=4/5   1/5 of work is completed in 3 days   total work wiil be done in   3*5= 
<gadget id="calculator">  3*5</gadget>
<output>15</output>
15 days   ANSWER:15
<result>B</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?