11. $$ \frac{2}{5d} - \frac{6d-4}{6-5d} = \frac{2(6-5d) - 5d(6d-4)}{5d(6-5d)} = \frac{12-10d - 30d^2+20d}{30d-25d^2} = \frac{12+10d - 30d^2}{30d-25d^2} $$
Ответ: $$ \frac{12+10d - 30d^2}{30d-25d^2} $$