已知x/2=y/3=z/4求2x+3y+4z/5x-2y

已知3x=4y,2y=5z,试求x:y:z 已知x:y:z=3:4:5,3x+2y-4z=18.求：x+y+z. 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知x/4=y/5=z/6 求x+y+z/3x-2y+z的值 已知x/4=y/5=z/6,求x+y+z/3x-2y+z的值. 已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y- 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+4y+3z=3x-2y-5z=0,求x+2y-z/2x-3y+7z的值 已知2x+3y-4z=0,3x+4y-5z=0.求x+y+z除以x-y+z, 已知{3x+4y+5z=0,2x+3y-4z=0,求x+y+z/x-y+z的值. 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/（除以）x-y+z的值. 已知2x+3y-4z=0,3x+4y+5z=0,求x+y+z/x-y+z的值.