19. \(\frac{a}{6a-12}+\frac{a}{5a-10}=\)

Разложим знаменатели: \(6a-12=6(a-2)\), \(5a-10=5(a-2)\). Тогда:

\(\frac{a}{6(a-2)}+\frac{a}{5(a-2)}=\frac{5a+6a}{30(a-2)}=\frac{11a}{30(a-2)}\).

Ответ: \(\frac{11a}{30(a-2)}\), \(a\ne2\).