Chapter 8 - Systems of Linear Equations and Problem Solving - 8.2 Solving by Substitution or Elimination - 8.2 Exercise Set - Page 516: 31

$(-1,2)$

Terms containing $y$ are opposite in the additive sense. Add the equations: $ 11x=-11\qquad$ ... and solve for $x$ $x=-1$ Substitute into one of the initial equations: $9x+3y=-3$ $9(-1)+3y=-3$ $3y=-3+9$ $3y=6$ $y=2$ Form an ordered pair $(x,y)$ as the solution to the system $(-1,2)$