1)9y²-6xy +(9y²-6xy)/(4x²-6xy)=(9y²-6xy)(4x²-6xy+1)/(4x²-6xy)=
=3y(3y-2x)(4x²-6xy+1)/2x(2x-3y)=-3y(4x²-6xy+1)/2x=(-12x²y+18xy²-3y)/2x
2)2x/(2x-3y)*(-12x²y+18xy²-3y)/2x=(-12x²y+18xy²-3y)/(2x-3y)
3)3y/3(x+y)+(-12x²y+18xy²-3y)/(2x-3y)=y/(x+y)+(-12x²y+18xy²-3y)/(2x-3y)=
=(2xy-3y²-12x³y+18x²y²-3xy-12x²y²+18xy³-3y²)/(x+y)(2x-3y)=
(6x²y²-12x³y+18xy³-xy-6y²)/(x+y)(3x-3y)