Applicare la formula: $\frac{a}{a}$$=1$, dove $a=y$ e $a/a=\frac{xy\cdot y}{\frac{5}{3}\cdot \frac{4}{3}y}$

Applicare la formula: $\frac{a}{b}\frac{c}{f}$$=\frac{ac}{bf}$, dove $a=5$, $b=3$, $c=4$, $a/b=\frac{5}{3}$, $f=3$, $c/f=\frac{4}{3}$ e $a/bc/f=\frac{5}{3}\cdot \frac{4}{3}$

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

Applicare la formula: $ab$$=ab$, dove $ab=5\cdot 4$, $a=5$ e $b=4$

Applicare la formula: $\frac{a}{\frac{b}{c}}$$=\frac{ac}{b}$, dove $a=xy$, $b=20$, $c=9$, $a/b/c=\frac{xy}{\frac{20}{9}}$ e $b/c=\frac{20}{9}$