P, Q and R can do a piece of work in 20, 30 and 60 days respectively. In how many days can P do the work if he is assisted by Q and R on every third day? Choices:	A) 15 DAYS	B) 12 DAYS	C) 10 DAYS	D) 18 DAYS	E) 20 DAYS
P's 2 day's work =	1/20*2=1/10   P+Q+R)'S 1 D15 DAYSY'S WORK = 1/20+1/30+1/60 = 6/60 = 1/10   WORK IN D15 DAYSYS = 1/5   NOW 1/5 DONE IN 3 D15 DAYSYS   WHOLE WORK WILL BE DONE IN(3*5)= 
<gadget id="calculator">(3*5)</gadget>
<output>15</output>
15 D15 DAYSYS   15 DAYSNSWER 15 DAYS
<result>A</result>
P, Q and R can do a piece of work in 20, 30 and 60 days respectively. In how many days can P do the work if he is assisted by Q and R on every third day?