Use properties of limits and algebraic methods to find the limit, if it exists. (If the limit is infinite, enter '?' or '-?', as appropriate. If the limit does not otherwise exist, enter DNE.) \\
$\lim_{x \to 3} f(x)$, where $f(x) = \begin{cases} 10 - 2x & \text{if } x < 3 \\ x^2 - x & \text{if } x \ge 3 \end{cases}$