Question

resolva os sistemas a segui sendo u e q a x+y= 20 x-y=60

Answer 1

{ x + y = 20
{ x - y = 60

{ x = 20
{ x = 60
-------------

2x = 80
x = 80/2
x = 40

x + y = 20
40 + y = 20
y = 20 - 40
y = - 20