what is 9 in a half times 9

$$\left({\mathtt{9}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right){\mathtt{\,\times\,}}{\mathtt{9}} = {\frac{{\mathtt{171}}}{{\mathtt{2}}}} = {\mathtt{85.5}}$$

i don't know