A. 5
B. 6
C. 7
D. 8
A and B can do a piece of work in 21 and 24 days respectively.They start the work together and after some days, A leaves and B completes the rest of the task in 9 days. After how many days did A leave?
A. 5
B. 6
C. 7
D. 8
A. 5
B. 6
C. 7
D. 8