①x／(3y)=2xy/(6y²)3x／(2y²)=9x/(6y²)②(x-y)／(2x+2y)=(x²-y²)/[2(x+y)²](x-y)／(x+y)²=2(x-y)/[2(x+y)²]③2mn／(4m²-9)2m／(2m+3)=2m(2m-3)/(4m²-9)...