$\frac{z^8{t}^4{w}^{20}}{z{t}^{3}w}=\frac{z^8}{z}\ast <!--\; \ast \; -->\frac{t^4}{t^3}\ast <!--\; \ast \; -->\frac{w^{20}}{w}=z^7{t}^3{w}^{19}$

$\frac{-<!--\; -\; -->m^{15}{n}^4{r}^8}{m^{19}{n}^{21}{r}^6}=-<!--\; -\; -->\frac{m^{15}}{m^{19}}\ast <!--\; \ast \; -->\frac{n^4}{n^{21}}\ast <!--\; \ast \; -->\frac{r^8}{r^6}=-<!--\; -\; -->\frac{r^2}{m^4{n}^{17}}$

$\frac{a^{12}{x}^{19}{z}^5}{-<!--\; -\; -->a^{40}{x}^{31}{z}^6}=-<!--\; -\; -->\frac{a^{12}}{a^{40}}\ast <!--\; \ast \; -->\frac{x^{19}}{x^{31}}\ast <!--\; \ast \; -->\frac{z^5}{z^6}=-<!--\; -\; -->\frac{1}{a^{28}{x}^{12}z}$

$\frac{-<!--\; -\; -->b^{100}{y}^{5}z}{-<!--\; -\; -->b^{101}{y}^3{z}^4}=\frac{b^{100}}{b^{101}}\ast <!--\; \ast \; -->\frac{y^5}{y^3}\ast <!--\; \ast \; -->\frac{z}{z^4}=\frac{y^2}{b{z}^3}$