Respuesta :

x = -3

So to figure this out we can readjust the equation to make it easier to solve

[tex]f(x) = x + 9[/tex] is equal to [tex]x+9 = 6[/tex]

From here we can just subtract 9 from both sides and we get our answer!

[tex]x+(9-9) = (6-9)\\x = -3[/tex]