Question

7m-{-m+3n-(5-n)-(-3+m]}-(2n+3)

Answer 1

7m-{-m+3m-5+n+3-m}-(2n+3)
7m-{m-2+n}-(2n+3)
7m-m+2-n-2n-3
6m-3n-1.

Te resulta 6m-3n-1 . Espero que se entienda :) saludos.