A, B and C can do a piece of work in 30 days, 30 days and 40 days respectively. They began the work together but C left 4 days before the completion of the work. In how many days was the work completed?
Options:	A) 12 days	B) 16 days	C) 18 days	D) 11 days	E) 38 days
One day work of A, B and C = 1/30 + 1/30 + 1/40 = 1/11Work done by A and B together in the last 4 days = 4*(1/30 + 1/30) = 4/15   Remaining work = 11/15   The number of days required for this initial work = 8 days.   The total number of days required = 4 + 8= 
<gadget id="calculator">4 + 8</gadget>
<output>12</output>
12 days.   12 daysnswer:12 days
<result>A</result>
A, B and C can do a piece of work in 30 days, 30 days and 40 days respectively. They began the work together but C left 4 days before the completion of the work. In how many days was the work completed?