Chapter 9 - Section 9.1 - Solving Systems of Linear Equations in Three Variables and Problem Solving - Exercise Set - Page 637: 14

$(-4, 5, -20)$

A: $x+2y=6$ B: $7x+3y+z=-33$ C: $x-z=16$ $x-z=16$ $x=16+z$ $x+2y=6$ $16+z+2y=6$ $2y+z=-10$ -7A+B $-7*(x+2y)+7x+3y+z=-7*6-33$ $-7x-14y+7x+3y+z=-42-33$ $-11y+z=-75$ $2y+z=-10$ $-11y+z=-75$ $2y+z=-10$ $z=-10-2y$ $-11y+z=-75$ $z=11y-75$ $-10-2y=11y-75$ $65=13y$ $65/13=13y/13$ $5=y$ $x+2y=6$ $x+2*5=6$ $x+10=6$ $x=-4$ $x-z=16$ $-4-z=16$ $-z=20$ $z=-20$