three numbers have a mean (average) of 7. the mode of these three numbers is 9. what is the smallest of these three numbers?

$${\frac{\left({\mathtt{9}}{\mathtt{\,\small\textbf+\,}}{\mathtt{9}}{\mathtt{\,\small\textbf+\,}}{\mathtt{x}}\right)}{{\mathtt{3}}}} = {\mathtt{7}} \Rightarrow {\mathtt{x}} = {\mathtt{3}}$$

X is the missing number.