(x+2)(x-9)-3x(3-2x)=x²+2x-9x-18-9x+6x²=7x²-16x-18 (a+5)(a-2)+(a+4)(a-5)=a²+5a-2a-10+a²+4a-5a-20=2a²+2a-30 (y-8)(2y+1)-(3y+1)(y-6)=2y²-16y+y-8-3y²-y+18y+6=-y²+2y-2