A and B can separately do apiece of work in 20 and 15 days respectively. They worked together for 6 days, after which B was replaced by C. If -the work was finished in next 4 days, then the number of days in which C alone could do the work will be  Choose the correct choice from the following answers:
A) 60
B) 40
C) 35
D) 30
E) 65
A and 40s one day work= 1/20+1/15=7/60   A and 40s six day work=(7/60)*6=7/10   remaining work=1-7/10=3/10   A and Cs 4 day work=(A and Cs 1 day work)*4= (1/20+1/x)*4=3/10 (remaining work)   x=40   Cs one day work=40   ANSWER:40
<result>B</result>
A and B can separately do apiece of work in 20 and 15 days respectively. They worked together for 6 days, after which B was replaced by C. If -the work was finished in next 4 days, then the number of days in which C alone could do the work will be