Question

resolva o sistema {x+y=7 x-y=1

Answer 1

X=4 Y=3 portanto, 4+3= 7 e 4-3=1

Answer 2

x+y=7
x-y=1 +
----------
2x+0=8
2x=8
x=8/2
x=4
e
x+y=7
4+y=7
y=7-4
y=3