Options :

1. $\frac{81}{80}\left({10}^n-1\right)+\frac{9}{8}n$

2. $\frac{81}{80}\left({10}^n-1\right)-\frac{9}{8}n$

3. $\frac{80}{81}\left({10}^n-1\right)+\frac{8}{9}n$

4. $\frac{80}{81}\left({10}^n-1\right)-\frac{8}{9}n$