3) (y-9)(3y-1)-(2y+1)(5y-7)
4) (4x-1)(4x-3)-(2x-10)(8x+1)

1)=3y^2-y-27y+9-(10y^2-14y+5y-7)=3y^2-y-27y+9-10y^2+14y-5y+7)=-7y^2-19y+16
2)16x^2-12x-4x+3-(16x^2+2x-80x-10)=16x^2-12x-4x+3-16x^2-2x+80x+10=62x+13