A, B and C can do a piece of work in 4 days, 8 days and 20 days respectively. How long will they taken, if all the three work together? Choose one
A) 2 B) 4 C) 5 D) 67 E) 2 6/17
1/4 + 1/8 + 1/20 = 17/40 =&gt; 40/17 =&gt; 2 6/17 days   Answer: 2 6/17
<result>E</result>
A, B and C can do a piece of work in 4 days, 8 days and 20 days respectively. How long will they taken, if all the three work together?