$$x^{2}+9x+px+pq; (x^{2}+9x)+(Px+P9x; x(x+9)+p(x+9); (x+9y)(x+p)$$
$\left(x+p\right)\left(x+q\right)\left(x^{2}+px+9x+pq\right)\left(x^{2}+px+qx+9p\right)$
$x^{2}+px+9x+pq,\ x^{2}+px+9x+pq,\ x\left(x+q\right)+p\left(x+9\right),\ \left(x+p\right)\left(x+q\right)$
