Question

mn-pk+mk-pn
___________
pk2-pn2

Answer 1

$\displaystyle \frac{mn-pk+mk-pn}{pk^{2}-pn^{2}}= \frac{m(n+k)-p(n+k)}{p(k-n)(k+n)}= \frac{(m-p)(n+k)}{p(k-n)(n+k)}= \\ \\ = \frac{m-p}{p(k-n)};$