You were the one who decided to make ! And once you found that t= 27 and t= 1 are roots, you should immediately realize that and . Isn't it clear what x must be?
(If it were something more complicated, say , you could use a logarithm: and then where the logarithm can be to any convenient base. But since both "3" and "27" are powers of 3, you were probably not intended to do that.)