Chapter 6 - Systems of Equations and Inequalities - Chapter Review - 6-2 Solving Systems Using Substitution - Page 405: 15

One solution $(-1,-2)$

$1/3y = 7/3*x + 5/3$ $x-3y = 5$ $1/3y = 7/3*x + 5/3$ $3*(1/3y = 7/3*x + 5/3)$ $y = 7x+5$ $x-3*(7x+5) = 5$ $x - 21x -15 = 5$ $-20x -15 = 5$ $-20x-15+15 = 5+15$ $-20x = 20$ $-20x/-20 = 20/-20$ $x= -1$ $x-3y= 5$ $-1 -3y = 5$ $-1-3y+1 = 5+1$ $-3y = 6$ $-3y/-3 = 6/-3$ $y = -2$