Question

Calcule o valor de X e Y
X+Y= 9
X-Y= 3

Answer 1

(1) X+Y= 9
(2) X-Y= 3

(1) X+Y= 9
     X= 9 -Y

(2) X-Y= 3
     (Se X= 9-Y)
     9-Y-Y= 3
     9- 2Y= 3
     9-3 = +2Y
     6 = 2Y
     Y = 6 

(1) X = 9-Y
     (Se Y = 6)
     X = 9-6
     X = 3

Logo:
X = 3
Y = 6