Step 1: First we have to write polynomials in descending order.
$$ \begin{aligned} P(x) &= 157 \\ Q(x) &= 2x+5 \\ \end{aligned} $$We can use distribution property to multiply the polynomial by the monomial.
$$ \begin{aligned} \color{blue}{157} \cdot \left( 2x+5 \right) &= \color{blue}{157} \cdot 2x + \color{blue}{157} \cdot 5 = \\ &= 314x+785 \end{aligned} $$