A can do a piece of work in 40 days; B can do the same in 30 days. A started alone but left the work after 10 days, then B worked at it for 10 days. C finished the remaining work in 10 days. C alone can do the whole work in?  Choose the correct choice
A) days B) days C) days D) 1/2 days E) days
Explanation:   10/40 + 10/30 + 10/x = 1   x = 24 days   daysnswer: days
<result>A</result>
A can do a piece of work in 40 days; B can do the same in 30 days. A started alone but left the work after 10 days, then B worked at it for 10 days. C finished the remaining work in 10 days. C alone can do the whole work in?