16^2m÷8^2n÷(4^m×4^3m-3n+1)
=2^8m÷2^6n÷(2^2m×2^(6m-6n+2))
=2^(8m-6n)÷(2^(8m-6n+2))
=2^(8m-6n-8m+6n-2)
=2^(-2)
=1/4