A alone can do a piece of work in 7 days, while B alone can do if in 10 days. In how many days will they complete the same work if they work together?

A

$$\frac{105}{17}$$ days

B

$$\frac{35}{17}$$ days

C

$$\frac{70}{17}$$ days

D

$$\frac{84}{17}$$ days