First, use this rule of exponents to combine or condense the terms within the parenthesis:
#x^color(red)(a) xx x^color(blue)(b) = x^(color(red)(a) + color(blue)(b))#
#(2n^color(red)(-2) * n^color(blue)(4))^4 = (2n^(color(red)(-2) + color(blue)(4)))^4 = (2n^2)^4#
Now, we can use these rules for exponents to complete the condensing:
#a = a^color(red)(1)# and #(x^color(red)(a))^color(blue)(b) = x^(color(red)(a) xx color(blue)(b))#
#(2n^2)^4 = (2^color(red)(1)n^color(red)(2))^color(blue)(4) = 2^(color(red)(1) xx color(blue)(4))n^(color(red)(2) xx color(blue)(4)) =2^4n^8 = 16n^8#