Chapter 3 - Section 3.1 - Systems of Linear Equations in Two Variables - 3.1 Exercises - Page 226: 27

$x=5$ $y=4$

First, we have to solve the second equation for $x$ and after that, we can substitute this expression in the first equation: $3-2y=-x$ $-3+2y=x$ $5x-4y=9$ $5(-3+2y)-4y=-15+6y=9$ $6y=24$ $y=4$ $-3+2y=-3+2(4)=5=x$ We need to check, if it is the right solution, we substitute x with $5$ and y with $4$: $5(5)-4(4)=9$ $\checkmark$ $3-2(4)=-5$ $\checkmark$