已知:3x=7y,则x:y=------------------

已知:3x=7y,则x:y=------------------ 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知｛3x+2y=3 2x+3y=7 ,则x+y= ,x-y= 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5x=7y,则x:y=( ) 已知3X=5Y,则X:Y= 已知1/x-1/y=3,则代数式x(2-7y)-y(7x+2)/x(1-y)-y(x+1)的值为多少. 已知x,y满足x²+y²-4x+6y+13=0则(3x+y)²-(3x+y)(3x-y)的 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 已知(x-y)/13=y/7,则（x+y）/y=