# How do you simplify 9m (m + n + 1) - 8 (m^2 + m - n)?

I found: ${m}^{2} + m + 8 n + 9 m n$
$= 9 {m}^{2} + 9 m n + 9 m - 8 {m}^{2} - 8 m + 8 n =$
$= {m}^{2} + m + 8 n + 9 m n$