Question

ajuda por favor para resolva esse sistema x+y=7 x-y=1

Answer 1

x+y=7
x-y=1

x=7-y
7-y-y=1
-2y=1-7
-2y=-6
y=6/2
y=3

x+y=7
x+3=7
x=7-3
x=4

S= {4,3}

Answer 2

7-y-y=1
-2y=-6 .(-1)
2y=6
y=3

x+3=7
x=4
s{(4,3)}