[tex](6x - 4 )*5 + 20-x ( 7 - 5 x )[/tex]
[tex]30x-20 + 20-x ( 7 - 5 x )[/tex]
[tex]30x-20 + 20-7x - 5x^{2}[/tex]
[tex]30x -7x + 5x^{2}[/tex]
[tex]23x + 5x^{2}[/tex]