(x+3y)/2=3/5与5(x-2y)=-4这题帮帮忙

(x+3y)/2=3/5与5(x-2y)=-4这题帮帮忙 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 关于X,Y的方程组3X+2Y=2m+5与x-y=4m-5的解x,y满足x+2y (3x+2y)+(5x-y)i=17-2i.求x与y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 2(x+y)-3(x-y) =1 6(x+y)+7(x-y)=51大神们帮帮忙 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 已知|2-x|与|x-y+4|互为相反数,求代数式3(x-y)-5(x-y)-3(x-y)+(y-x)-4(x+y)+3 初二化简求值题[（5x+2y)(3x+2y)+(x+2y)(x-2y)]/4x,其中x=2,y=3 解二元一次方程组,用消元法{3x+4y=5,{-7x+9y=-5／2帮帮忙啊