## Elementary Linear Algebra 7th Edition

$x = 6$ $y = -3$ (6, -3)
$x-5y=21$ $6x+5y=21$ Add the equations. $x - 5y + (6x + 5y) = 21 + 21$ $x + 6x -5y + 5y = 42$ $7x = 42$ $x = 42/7$ $x = 6$ Substitute x in the first equation to get y $6 - 5y = 21$ $-5y = 15$ $y = -3$