If A, B and C together can finish a piece of work in 4 days. A alone in 12 days and B in 18 days, then C alone can do it in?  Choices
A) 21 days	B) 15 days	C) 12 days	D) 9 days	E) 6 days
Explanation:   C = 1/4 - 1/12 – 1/18 = 1/9 =&gt; 9 days   Answer: 9 days
<result>D</result>
If A, B and C together can finish a piece of work in 4 days. A alone in 12 days and B in 18 days, then C alone can do it in?