x/2=y/3=z/（-5）,求（2x+y+3z）/2x的值

已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/（除以）x-y+z的值. x+2y=3x+2z=4y+z 求x:y:z x+y+z=35 2x-y=5 y/3=z/2 求x,y,z 1.已知x:y:z=4:5:7,求：（一）2x+3y+z/5z； （二）x+y/y+z 非常急, 设|x|-|y|+|z|=|x+y+z|,且|x+y|=4,|y+z|=5,|y|=3,求(x-y-z)^2的值 方程组x+y=5,x+z=-2,z+x=3 求x+y+z等于 3x-y=-7,y+2z=2,2x-2z=-5 求x,y,z x+y-z=5,2x+3y+z=10,x-2y-z=20求方程组 2x+Y+3z=23,x+4y+5z=36,求X+2Y+3z~ 2x+y-z=3 5x+3y-z=10 求x+y+z= x:y:z=2:1:5,2x+3y-z=18,求x,y,z,值 2分之x=3分之y=5分之z x+y+z=20 求x,y,z 已知{x-5y+2z=0 3x-5y-4z=0,求x：y:z 若x/3=y/4=z/5,求x+y+z/3x-2y+z的值. x/3=y/4=z/5,求x+y+z/3x-2y+z的值, x+2y+3z=20,x+3y+5z=31,求x+y+z的值