Сократите дроби:
а) $\frac{10 * 9}{30 * 9}$;
б) $\frac{12 * 14 * 16}{14 * 16 * 18}$;
в) $\frac{14 * 15}{21 * 20}$;
г) $\frac{5 * 9}{6 * 7 * 30}$.
$\frac{10 * 9}{30 * 9} = \frac{10 * 9}{(3 * 10) * 9} = \frac{1}{3}$
$\frac{12 * 14 * 16}{14 * 16 * 18} = \frac{(6 * 2) * 14 * 16}{14 * 16 * (6 * 3)} = \frac{2}{3}$
$\frac{14 * 15}{21 * 20} = \frac{(2 * 7) * (3 * 5)}{(3 * 7) * (4 * 5)} = \frac{2}{4} = \frac{2 * 1}{2 * 2} = \frac{1}{2}$
$\frac{5 * 9}{6 * 7 * 30} = \frac{5 * (3 * 3)}{(2 * 3) * 7 * (2 * 3 * 5)} = \frac{1}{2 * 7 * 2} = \frac{1}{28}$