Question

resolvemos x + y = 5 x - y = 7 indica :3x + y​

Answer 1

x+y=5⇒x=5-y=5-(-1)=5+1=6

x-y=7

5-y-y=7

5-2y=7

5-7=2y

-2=2y

-1=y

x=6

y= -1

3x+y=3·6+(-1)=18+(-1)=18-1=17