Respostas

2014-08-27T17:12:52-03:00
X+y =75
x-y =9
2x = 84
x=42

42+y = 75
y = 75-42
y = 33
1 5 1
2014-08-27T17:13:42-03:00
{x+ y = 75
{x - y = 9

2x = 84 ⇒ x = 42 
42 - y = 9 ⇒ y = -9 + 42 = 33
1 5 1