## Elementary Algebra

$-30x^{5n}$
Using the law $a^{m}\times a^{n}=a^{m+n}$ to obtain: $(-6x^{2n+4})(5x^{3n-4})$ $=(-6\times 5)(x^{2n+4}\times x^{3n-4})$ $=(-30)(x^{2n+4+3n-4})$ $=-30x^{5n}$