(3x+2y−9)(2x−6y+2)−[(4x−9y−1)+(−3x+8y+7)]
=3x(2x−6y+2)+2y(2x−6y+2)−9(2x−6y+2)−[4x−9y−1−3x+8y+7]
=6x2−18xy+6x+4xy−12y2+4y−18x+54y−18−[x−y+6]
=6x2−18xy+6x+4xy−12y2+4y−18x+54y−18−x+y−6
=6x2−12y2+6x−18x−x+4y+54y+y−18xy+4xy−18−6
=6x2−12y2−13x+59y−14xy−24
Simplify: (3x−2y)(3x+4y)−(3x+2y)(3x−2y)