A and B can do a piece of work in 4 days, B and C in 5 days, C and A in 6 days. How long will C take to do it?  Select the correct option
A) 140/11 days  B) 120/7 days  C) 100/13 days  D) 80/7 days  E) 60/7 days
2c = 1/5 + 1/6 – 1/4 = 7/60   c = 7/120 =&gt; 120/7 days   The answer is 120/7 days.
<result>B</result>
A and B can do a piece of work in 4 days, B and C in 5 days, C and A in 6 days. How long will C take to do it?