If A, B and C together can finish a piece of work in 4 days. A alone in 12 days and B in 9 days, then C alone can do it in?	Choose the correct answer
A) 11 B) 17 C) 18 D) 19 E) 16
18 = 1/4 - 1/12 – 1/9 = 1/18 =&gt; 18 days'   Answer: 18
<result>C</result>
If A, B and C together can finish a piece of work in 4 days. A alone in 12 days and B in 9 days, then C alone can do it in?