Applicare la formula: $\frac{a^m}{a^n}$$=a^{\left(m-n\right)}$, dove $a^n=y^{\left(3a-7\right)}$, $a^m=y^{\left(3a+5\right)}$, $a=y$, $a^m/a^n=\frac{y^{\left(3a+5\right)}}{y^{\left(3a-7\right)}}$, $m=3a+5$ e $n=3a-7$

Applicare la formula: $-\left(a+b\right)$$=-a-b$, dove $a=3a$, $b=-7$, $-1.0=-1$ e $a+b=3a-7$

Applicare la formula: $a+b$$=a+b$, dove $a=5$, $b=7$ e $a+b=3a+5-3a+7$

Annullare i termini come $3a$ e $-3a$