Applicare la formula: $ab$$=ab$, dove $ab=3\cdot 5\cdot \left(\frac{3}{5}\right)$, $a=3$ e $b=5$

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=3$, $b=5$, $c=15$, $a/b=\frac{3}{5}$ e $ca/b=15\cdot \left(\frac{3}{5}\right)$

Applicare la formula: $ab$$=ab$, dove $ab=15\cdot 3$, $a=15$ e $b=3$

Applicare la formula: $\frac{a}{b}$$=\frac{a}{b}$, dove $a=45$, $b=5$ e $a/b=\frac{45}{5}$