A can finish a work in 16 days and B can finish the same work in 15 days. After A had worked for 4 days, B also joined A to finish the remaining work. In how many days will the remaining work be finished?

A

$$5\frac{25}{31}$$

B

$$7\frac{25}{31}$$

C

$$8\frac{25}{31}$$

D

$$6\frac{25}{31}$$