Chapter 3 - Section 3.1 - Systems of Linear Equations in Two Variables - 3.1 Exercises - Page 226: 23

$x=2$ $y=3$

Equation 2 is already solved for y, we substitute y in the first equation, with the expression in the second: $-x-4y=-14$ $-x-4(2x-1)=-9x+4=-14$ $-9x=-18$ $x=2$ $y=2x-1=3$ We need to check, if it is the right solution, we substitute x with 2 and y with 3: $-2-4(3)=-14$ $\checkmark$ $3=2(2)-1$ $\checkmark$