A can do a piece of work in 6 days. B can do it in 5 days. With the assistance of C they completed the work in 2 days. Find in how many days can C alone do it?
Choose the correct option:	A) 8.7 days	B) 2.0 days	C) 6.6 days	D) 7.5 days	E) 4.4 days

Rationale: "c = 1 / 2 - 1 / 6 - 1 / 5 = 2 / 15 = > 7.5 days answer : d"
Answer: D