Question

Me Ajudem Pfv .......

Answer 1

x+y=12 (-1)
x-2y=-3

-x-y=-12 ==> -x-5=-12 => -x=-7 => x=7
x-2y=-3
========> -3y= -15
y= 5

Answer 2

x+y= 12 => x=12-y
x-2y= -3 => 12-y-2y= -3

12-y-2y= -3
15= 3y
y=15/3
y=5