Повторюємо алгебру за 8 клас: 3

1) $\frac{x+y}{5}$ – $\frac{x}{5}$ = $\frac{x+y-x}{5}$ = $\frac{y}{5}$;

3) $\frac{12}{x^2}$ • $\frac{x}{3}$ = $\frac{12x}{3x^2}$ = $\frac{4}{x}$;

2) $\frac{4m^2}{5}$ + $\frac{m^2}{5}$ = $\frac{5m^2}{5}$;

4) $\frac{a^2}{3}$ : $\frac{a}{15}$ = $\frac{a^2}{3}$ • $\frac{15}{a}$ = $\frac{15a^2}{3a}$ = $\frac{5a}{3}$.