Chapter 4 - Polynomials - 4.1 Exponents and Their Properties - 4.1 Exercise Set - Page 236: 46

$3r^{8}s^{6}$

Using $\dfrac{a^x}{a^y}=a^{x-y}$, then the expression, $ \dfrac{12r^{10}s^7}{4r^2s} $, simplifies to \begin{array}{l}\require{cancel} \dfrac{\cancel{4}\cdot3r^{10-2}s^{7-1}}{\cancel{4}} \\\\= 3r^{8}s^{6} .\end{array}