Exponents multiply when they are outside of parenthesis (Example: (x^4)^3=x^12) and add when they are on the same variable being multiplied (Example: (x^4)(x^3)=(x^7).
In this case, the -4 outside of the parenthesis multiplies to both the numerator and the denominator. Careful to pay attention to both numbers on the top though! The -4 applies to the 3 and the x^-4 separately. After multiplying that through, you have:
A negative exponent becomes positive when you switch the number to the other side of the fraction (numerator to denominator or vice versa). Let's do that with the 3^-4.
Now multiply out the 3^4 to get the final answer: