A and B can do a work in 21 days and 14 days, respectively. They started the work by working together, but after 5 days, due to some reasons, B left the work and A completed the remaining work. The whole work was completed in:
1
\(10\frac{1}{2}\) days
2
13 days
3
\(12\frac{1}{2}\) days
4
\(13\frac{1}{2}\) days