[tex]\qquad \qquad\huge \underline{\boxed{\sf Answer}}[/tex]
let's simply the expression ~
[tex]\qquad \sf \dashrightarrow \: 10( - 8x + 7) - 9x[/tex]
[tex]\qquad \sf \dashrightarrow \: (- 80x + 70 )- 9x[/tex]
[tex]\qquad \sf \dashrightarrow \: - 80x - 9x + 70[/tex]
[tex]\qquad \sf \dashrightarrow \: - 89x + 70[/tex]
Hope it helps ~
