Сократите дроби: a) $$rac{24}{72}$$; б) $$rac{5 cdot 9}{18 cdot 15}$$.

a) $$rac{24}{72} = rac{24:24}{72:24} = rac{1}{3}$$.

б) $$rac{5 cdot 9}{18 cdot 15} = rac{5 cdot 9}{2 cdot 9 cdot 3 cdot 5} = rac{1}{2 cdot 3} = rac{1}{6}$$.