已知x-2y=3,则-3x+6y=?

已知x-2y=3,则(2x+y-6)/(3x-y-9)=? 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x,y为实数,根号3x+4 +y^2-6Y+9=0则x+y=? 已知x-5y=0(y≠0）,则代数式2x-3y/3x+6y 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知x,y满足x²+y²-4x+6y+13=0则(3x+y)²-(3x+y)(3x-y)的 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 已知x-2y/2x+3y=3/4,则x：y= 已知3x-3=2y-3,则x-y/x+y等于多少 已知x-2y/3y-x=2/3,则y/x的值是