First group the coefficients and variables.

4m⁴(n⁷m) =  4n⁷(m⁴ · m)

Since base is common, apply the product of powers property: a^m · aⁿ = a^{m + n}.

=  4n⁷ m^{4 + 1}

=  4n⁷m⁵              (Add exponents: 4 + 1 = 5)

Product of  Product of 4m⁴(n⁷m) is 4n⁷m⁵.