Question 1042181
{{{2*5(x+2y)(2y-x)^2-4*3(2y+x)(x-2y)}}}


{{{2*5(x+2y)(2y-x)^2-2*2*3*(-1)(2y+x)(2y-x)}}}


{{{2*5*(x+2y)(2y-x)^2+2*2*3(2y+x)(2y-x)}}}


That much was done just to show the adjustment using the factor {{{-1}}}.  You do the rest of this.