Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=7$, $b=8$, $c=-3$, $a/b=\frac{7}{8}$ e $ca/b=-3\cdot \left(\frac{7}{8}\right)$

Applicare la formula: $ab$$=ab$, dove $ab=-3\cdot 7$, $a=-3$ e $b=7$

Applicare la formula: $\frac{a}{b}+\frac{c}{b}$$=\frac{a+c}{b}$, dove $a=-21$, $b=8$ e $c=5$

Applicare la formula: $a+b$$=a+b$, dove $a=-21$, $b=5$ e $a+b=-21+5$

Applicare la formula: $\frac{a}{b}$$=\frac{a}{b}$, dove $a=-16$, $b=8$ e $a/b=-\frac{16}{8}$