TeX source:

\Pr\{i|\mathcal{E}\} = \color{red}{\Pr\{\mathcal{E}|i\}}\dfrac{p_i}{\Pr\{\mathcal{E}\}} = \color{red}{\text{tr}\{\mathcal{E}(\rho_i)\}}\dfrac{p_i}{\Pr\{\mathcal{E}\}}.