Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=4$, $b=7$, $c=5$, $a/b=\frac{4}{7}$ e $ca/b=5\frac{4}{7}a^2b^7ab^x$

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

Applicare la formula: $x^mx^n$$=x^{\left(m+n\right)}$, dove $x=b$, $m=7$ e $n=x$

Applicare la formula: $x\cdot x^n$$=x^{\left(n+1\right)}$, dove $x^nx=\frac{20}{7}a^2b^{\left(7+x\right)}a$, $x=a$, $x^n=a^2$ e $n=2$

Applicare la formula: $a+b$$=a+b$, dove $a=2$, $b=1$ e $a+b=2+1$