A and B can do a piece of work in 10 days. With the help of C they finish the work in 5 days. C alone can do that piece of work in?	Choose one:
A) 15.5 days
B) 19.5 days
C) 10 days
D) 16.5 days
E) 18.5 days
10 days = 1/5 – 1/10 = 5/50 =&gt; 10 days   ANSWER:10 days
<result>C</result>
A and B can do a piece of work in 10 days. With the help of C they finish the work in 5 days. C alone can do that piece of work in?