A can do a piece of work in 30 days; B can do the same in 30 days. A started alone but left the work after 10 days, then B worked at it for 10 days. C finished the remaining work in 10 days. C alone can do the whole work in?  Choose the correct choice from the following options:
A) 30 days	B) 65 days	C) 86 days	D) 45 days	E) 17 days

Rationale: 10 / 30 + 10 / 30 + 10 / x = 1 x = 30 days answer : a
Answer: A