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?  Choose the correct choice from the following.
A) 33
B) 20
C) 88
D) 77
E) 11
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?