Simplify the Rational Expression $\frac { n r - 10 - 2 n + 5 r } { n r + 20 + 5 r + 4 n }$

Simplify the rational expression. You will need to use factoring by grouping. $\frac { n r - 10 - 2 n + 5 r } { n r + 20 + 5 r + 4 n }$