(x-18)÷18/y=(x-27)÷27/2y

[x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 「（x²+y²）-（x-y）²+2y（x-y）」÷4y,其中2x-y=18 已知2y-3x+3=0 求(2y-3x)^3x-2y+3（3x-2y)-18÷（2y-3x) 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y x+y-z=0 x+2y-z=3 2x-3y+2z=5 y÷3-x+1÷6=3 2（x-y÷2))=3(x+y÷18) 1.[(x-y)^2-2(y -x)]÷(x-y) 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 解方程组27/(3X-2Y)-2/(-2X+3Y)=1 18/(3X-2Y)+11/(2X-3Y)=13 已知(x-y)÷4=(2x+y)=5,且2x-3y=18,求3x-5y的值. 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y