Step 1: Write second polynomial below the first one. Making sure like terms are lined up.
$$ \begin{array}{lrr} & -4x & -19 \\ \color{blue}{ + } & 13x & 7 \\ \hline \end{array} $$Step 2: Combine like terms (add each column):
$$ \begin{array}{lrr} & -4x & -19 \\ \color{blue}{ + } & 13x & 7 \\ \hline & 9x & -12 \end{array} $$