rút gọn biểu thức (3-5x)(5x+3)+(5x-7)^2-69x

`(3-5x)(5x+3)+(5x-7)^2-69x`

`=3(5x+3)-5x(5x+3)+(25x^2-70x+49)-69x`

`=15x+9-25x^2-15x+25x^2-70x+49-69x`

`=(25x^2-25x^2)+(15x-15x-70x-69x)+(9+49)`

`=-139x+58`