Question

respostas 2x+8Y==7 X-8Y=4

Answer 1

$\left \{ {{2x + 8y = 7} \atop {x-8y=4}} \right.$

8y = 7 - 2x
x - 8(7 - 2 x) = 4
x - 56 + 16x = 4
x - 16x = 4 + 56
-15x = 60 
x = $\frac{60}{-15}$
x = -4 

Substituindo 

x - 8y = 4
-4 - 8y = 4
-8y = 4 + 4
-8y = 8
y = $\frac{8}{-8}$
y = -1

x = -4 e y = -1