Question

MÉTODO DA COMPARAÇÃO
3 x+y= 19
x+y= 15

Answer 1

3 x + y = 19
y = 19 - 3 x

x + y = 15
y = 15 - x

19 - 3 x = 15 - x
 -3 x + x = 15 - 19
-2 x = -4
x = -4/-2
x = +2

x + y = 15
2 + y = 15
y = 15 - 2
y  = 13