A and B can do a piece of work in 3 days, B and C in 4 days, C and A in 5 days. How long will C take to do it?  Select the correct option:
A) 120/7 days	B) 110/11 days	C) 100/9 days	D) 90/13 days	E) 80/3 days
2c = 1/4 + 1/5 – 1/3 = 7/60   c = 7/120 =&gt; 120/7 days   The answer is 120/7 days.
<result>A</result>
A and B can do a piece of work in 3 days, B and C in 4 days, C and A in 5 days. How long will C take to do it?