A can do a piece of work in 40 days; B can do the same in 40 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 option.
A) 20 days B) 65 days C) 86 days D) 45 days E) 17 days
10/40 + 10/40 + 10/x = 1   x = 20 days   20 daysnswer:20 days
<result>A</result>
A can do a piece of work in 40 days; B can do the same in 40 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?