Chapter 9 - Section 9.1 - Solving Systems of Linear Equations in Three Variables and Problem Solving - Practice - Page 634: 5

$(-5, 2, -10)$

A: $2x+5y-3z=30$ B: $x+y = -3$ C: $2x-z=0$ C $2x-z=0$ $2x=z$ A $2x+5y-3z=30$ $2x+5y-3(2x)=30$ $2x+5y-6x=30$ $-4x+5y=30$ $x+y=-3$ $-4x+5y=30$ $4*(x+y)+(-4x+5y)=4*(-3)+30$ $4x+4y-4x+5y=-12+30$ $4y+5y=18$ $9y=18$ $9y/9=18/9$ $y=2$ $x+y=-3$ $x+2=-3$ $x=-5$ $2x-z=0$ $2(-5)-z=0$ $-10-z=0$ $-10=z$