Two men X and Y working together, completed a job in 6 days. If X had worked thrice as efficiently as he actually worked and Y had worked one-fomth as efficiently as he acn,ally worked, the work would have been completed in 4 days. In how many days X alone could complete the work?

A

$$12\frac{6}{5}$$

B

$$8\frac{1}{2}$$

C

$$9\frac{1}{3}$$

D

$$10\frac{1}{5}$$