You have the following expression:
(3⁻⁸)/(3⁻⁴)
in order to simplify the previous expression, consider that the quotient in between two number with the same base is given by:
Hence, for the given expression, you have:
moreover, consider that any number with a negative exponent can be written as 1 over the same number with positive exponent, then, you have:
Hence, the simplified expression is 1/3⁴, or 3⁻⁴