A can do a piece of work in 4 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?
Pick
A) 10	B) 20	C) 5	D) 4	E) 6
C = 1/2 - 1/4 - 1/5 = 1/20 =&gt; 20 days   ANSWER 20
<result>B</result>
A can do a piece of work in 4 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?