Question

$left { {{x-2y=3} atop {5x+y=4}} right.$

Answer 1

$left { {{x = 3 + 2y} atop {5(3 + 2y) + y = 4}} right.$
$left { {{x = 3 + 2y} atop {15 + 11y = 4}} right.$
$left { {{x = 3 + 2y} atop {11y = -11}} right.$
$left { {{x = 3 + 2y} atop {y = -1}} right.$
$left { {{x = 1} atop {y = -1}} right.$