Applicare la formula: $\frac{a}{b}\frac{c}{f}$$=\frac{ac}{bf}$, dove $a=x$, $b=2$, $c=4$, $a/b=\frac{x}{2}$, $f=x$, $c/f=\frac{4}{x}$ e $a/bc/f=\frac{x}{2}\frac{4}{x}$

Applicare la formula: $\frac{a}{a}$$=1$, dove $a=x$ e $a/a=\frac{4x}{2x}$

Applicare la formula: $\frac{a}{a}$$=1$, dove $a=x$ e $a/a=\frac{4x}{2x}$

Applicare la formula: $\frac{a}{b}$$=\frac{a}{b}$, dove $a=4$, $b=2$ e $a/b=\frac{4}{2}$