A and B working separately can do a piece of work in 21 and 24 days, respectively. If they work for a day alternately with A beginning the work, it would be completed in _________.
1
24\(\frac{1}{8}\) days
2
22\(\frac{3}{8}\) days
3
22\(\frac{2}{5}\) days
4
22\(\frac{1}{8}\) days