Applicare la formula: $\frac{a^n}{a}$$=a^{\left(n-1\right)}$, dove $a^n/a=\frac{-3x^7y^2}{21xy}$, $a^n=x^7$, $a=x$ e $n=7$

Applicare la formula: $\frac{a^n}{a}$$=a^{\left(n-1\right)}$, dove $a^n/a=\frac{-3x^{6}y^2}{21y}$, $a^n=y^2$, $a=y$ e $n=2$

Applicare la formula: $\frac{ab}{c}$$=\frac{a}{c}b$, dove $ab=-3x^{6}y$, $a=-3$, $b=x^{6}y$, $c=21$ e $ab/c=\frac{-3x^{6}y}{21}$