Question

mn-pk+mk-pn
___________
pk2-pn2

Answer 1

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