Step 1: First we have to write polynomials in descending order.
$$ \begin{aligned} P(x) &= -7w^2+4w+5 \\ Q(x) &= 3w^2-14 \\ \end{aligned} $$Step 2: Write second polynomial below the first one. Making sure like terms are lined up.
$$ \begin{array}{lrrr} & -7w^2 & 4w & 5 \\ \color{blue}{ + } & 3w^2 & & -14 \\ \hline \end{array} $$Step 3: Combine like terms (add each column):
$$ \begin{array}{lrrr} & -7w^2 & 4w & 5 \\ \color{blue}{ + } & 3w^2 & & -14 \\ \hline & -4w^2 & 4w & -9 \end{array} $$