求x,y的值,使3(0.5x-1)-8y=-x+0.5y=-7(写出解题过程)

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 3(x-5)-8y=-x-(-0.5y)=7,求x,y的值 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 (-x+6):(x-y);(4x+y)=3;14:1,求x+y的值. (x+y)+(2x+0.5y)+(3x+1/6y)+...+(9x+1/72y),当x=2,y=9时,求代数式的值 已知x.x+y.y-6x-8y+25=0,求3x.x+5y的值 已知(3x+1)(3x-3)-3x+2)^2=-7,(y+7)(y-7)-y(y-7)=0,求8y^2-5y(-y+3x)+4y(-4y-5/2x)的值 已知x,y为正整数,并且x*y+x+y=71,x*x*y+x*y*y=880,求3*x*x+8*x*y+3*y*y的值 已知x^2-8x+y^2-y+16又1/4=0,求[(x+y)(x-y)-(x+y)^2-2y(x-3y)]÷4y的值 2x+3y-1=y-x-8=x+6求2x-y的值 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 1 已知x+y/y=7/3 求x+y/x-y等于什么2 若x+4/3=y+3/2=z+8/4 且x+y+z=12 求x、y、z的值 已知x-y/y=8/3,求x+y/y的值 X+Y-8X+10Y+41=O,求X/Y-Y/X的值 已知x-y=8,（x+y)(x-y)=32,求x,y的值 求x,y的值,使3(0.5x-1)-8y=-x+0.5y=-7(写出解题过程) |x-y+3|与|x+y-1999|互为相反数,求x+y/x-y的值