A and B can do a piece of work in 9 days. With the help of C they finish the work in 5 days. C alone can do that piece of work in?  Choices:  A) 11.25 days  B) 19.5 days  C) 17.5 days  D) 16.5 days  E) 18.5 days
C = 1/5 – 1/9 = 4/45 =&gt; 11.25 days   11.25 daysNSWER:11.25 days
<result>A</result>
A and B can do a piece of work in 9 days. With the help of C they finish the work in 5 days. C alone can do that piece of work in?