若2x+3y=4,2y+3x=7,则x-y的值为?

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 若2x=3y,则(x*x+y*y)/x*x=? 若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若x+3y=3x+2y=7,则x+y=几? 若x/y=4/3 则3x+2y/2x-5y= 2（x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1