Respuesta :
subsitute 9 for y
9=y=9x-9
add 9 to both sides
9+9=9x+9-9
18=9x+0
18=9x
divide by 9
2=x
y=9
x=2
9=y=9x-9
add 9 to both sides
9+9=9x+9-9
18=9x+0
18=9x
divide by 9
2=x
y=9
x=2