1. b-4d 2d+b -- -- = 6 10

1. $$ \frac{b-4d}{6} - \frac{2d+b}{10} = \frac{5(b-4d) - 3(2d+b)}{30} = \frac{5b-20d-6d-3b}{30} = \frac{2b-26d}{30} = \frac{b-13d}{15} $$

Ответ: $$ \frac{b-13d}{15} $$