Chapter 6 - Systems of Equations and Inequalities - Chapter Review - 6-3 and 6-4 Solving Systems Using Elimination; Applications of Systems - Page 406: 21

One solution $(-11,-7)$

$5x + 4y = -83$ $3x-3y = -12$ $3x-3y = -12$ $1/3*(3x-3y = -12)$ $x-y = -4$ $x-y+y = -4+y$ $x = y-4$ $5*(y-4)+4y = -83$ $5y - 20+4y = -83$ $9y - 20 = -83$ $9y-20+20 = -83+20$ $9y = -63$ $9y/9 = -63/9$ $y= -7$ $5x+4y = -83$ $5x+4*(-7)=-83$ $5x -28 = -83$ $5x -28+28 = -83+28$ $5x = -55$ $5x/5 = -55/5$ $x = -11$