n has a negative exponent, so you need to rewrite the expression using the negative exponent rule b^-n = 1/b^n
(m^8 1/n^4)^1/4
Now make m^8 a fraction buy giving it a denominator of 1:
(m^8 / 1 1/n^4)^1/4
Multiply the fractions together to get m^8/n^4
Now divide the exponents by 4 to get the final answer of:
m^2/n