Question

x+y=9
x-y=5

4×-y=8
×+y=7
​

Answer 1

X=9-y

9-y-y=5
-2y=5-9
-2y=-4(.-1)
Y=4/2=2
Substitui na equação
X+2=9
X=7






4x-y=8
X=8+y/4
8+y/4 +y=7
8+y +4y /4=7
5y=7-8
Y=-1/5
Substitui
X-1/5=7

5x-1/5=7
5x=35+1
X=36/5