Question

alguem responde por favor x=7-y x-y=1

Answer 1

(I) x=7-y  --> (y=3) --> x=7-3  x=4
(II) x-y=1 --> x=1+y

(I)1+y=7-y       
2y=6
y=3
  
 S={y=3, x=4}