minus, $6,$ left parenthesis, minus, $5,$ m$,$ minus, $3,$ n$,$ right parenthesis, plus, $8,$ n$,$ minus, $3,$ left parenthesis, minus, $3,$ n$,$ plus, $4,$ m$,$ right parenthesis $-6(-5$m$-3$n$)+8$n$-3(-3$n$+4$m$)$