Answer :

Divide both sides by 2³. Remember, when dividing exponent terms with the same base, you subtract the exponents. 

You're then left with [tex]2^{n} [/tex] = [tex] 2^{6} [/tex]

Therefore, n = 6
[tex]2^{3} + 2^{n} = 2^{9}[/tex]
[tex]8 + 2^{n} = 512[/tex]
[tex]- 8[/tex]    [tex]- 8[/tex]
------------------------------
[tex]2^{n}) = 504[/tex]
[tex]ln(2^{x}) = ln(504)[/tex]
[tex]xln(2) = ln(504)[/tex]
[tex]x = \frac{ln(504)}{ln(2)} [/tex]