Question

1)Resolva os Sistemas

x-y=4
x+y=20

Answer 1

{x-y=4 x-y=4


{x+y =20 12-y=4
------------
2x= 24 -y= -12 + 4
x=24/2 -y=-8
x=12
y=8

Answer 2

Vamos la

x . y = 4

x + y = 20

adiçao

2x = 24,   x = 24/2 = 12

12 + y = 20

y = 20 - 12 = 8

S = (12, 8)