Chapter 3 - Section 3.1 - Systems of Linear Equations in Two Variables - 3.1 Exercises - Page 226: 29

$x=1$ $y=3$

First, we have to solve the second equation for $x$ and after that, we can substitute this expression in the first equation: $x+2y=7$ $x=7-2y$ $4x-5y=-11$ $4(7-2y)-5y=-11$ $28-13y=-11$ $y=3$ $x=7-2(3)=1$ We need to check, if it is the right solution, we substitute x with $1$ and y with $3$: $1+2(3)=7$ $\checkmark$ $1=7-2(3)$ $\checkmark$