3x+4y+5z=30000

已知3X=4X,5Y=6Z求X+Y：Y+Z (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 已知x:y:z=3:4:5,3x+2y-4z=18.求：x+y+z. 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? {2x+3y-4z=-5 x+y+z=6 x-y+3z=10 若3x+7y+z=5,4x+10y+z=3,则x+y+z=? 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z x/3=y/4=z/5,求x+y+z/3x-2y+z的值, 若x/3=y/4=z/5,求x+y+z/3x-2y+z的值. 3x+7y+z=5 ,4x+10y+z=6 ,x+y+z= 2x+5y+4z=0,3x+y-7z=0,则x+y-z=? 已知x+y=3，y+z=4，x+z=5，则x+y+z等于（　　）