Решим уравнение:
$$\frac{3x - 4}{6} = \frac{7}{8}$$ $$3x - 4 = \frac{7 \cdot 6}{8}$$ $$3x - 4 = \frac{42}{8}$$ $$3x - 4 = \frac{21}{4}$$ $$3x = \frac{21}{4} + 4$$ $$3x = \frac{21 + 16}{4}$$ $$3x = \frac{37}{4}$$ $$x = \frac{37}{4} : 3$$ $$x = \frac{37}{4 \cdot 3}$$ $$x = \frac{37}{12}$$ $$x = 3\frac{1}{12}$$Ответ: $$3\frac{1}{12}$$