Factorize each of the following algebraic expression:

$25-p^{2}-q^{2}-2 p q$

$=25-\left(\mathrm{p}^{2}+2 \mathrm{pq}+\mathrm{q}^{2}\right)$

$=5^{2}-\left(\mathrm{p}^{2}+2 \times \mathrm{p} \times \mathrm{q}+\mathrm{q}^{2}\right)$

$=5^{2}-(\mathrm{p}+\mathrm{q})^{2}$

$=[5-(\mathrm{p}+\mathrm{q})][5+(\mathrm{p}+\mathrm{q})]$

$=(5-\mathrm{p}-\mathrm{q})(5+\mathrm{p}+\mathrm{q})$

$=-(\mathrm{p}+\mathrm{q}-5)(\mathrm{p}+\mathrm{q}+5)$