Chapter 5 - Systems of Equations and Inequalities - Exercise Set 5.1 - Page 527: 39

(-5, -1)

Plug x + 4y = -9 into $\frac{x}{4} - \frac{y}{4} = -1$ x = -9 - 4y $\frac{-9 - 4y}{4} - \frac{y}{4} = -1$ $\frac{-9 - 5y}{4} = -1$ -9 - 5y = -4 -5y = 5 y = -1 Plug y into x + 4y = -9 x + 4$\times -1$ = -9 x - 4 = -9 x = -5