Решение:

$$1 \frac{1}{4} = \frac{5}{4}$$

$$2 \frac{1}{8} = \frac{17}{8}$$

Подставим значения в выражение:

$$(1.4 - 3.5 : \frac{5}{4}) : 2.4 + 3.4 : \frac{17}{8} = (1.4 - 3.5 \cdot \frac{4}{5}) : 2.4 + 3.4 \cdot \frac{8}{17} $$

$$3.5 \cdot \frac{4}{5} = \frac{35}{10} \cdot \frac{4}{5} = \frac{7}{2} \cdot \frac{4}{5} = \frac{28}{10} = 2.8$$

$$3.4 \cdot \frac{8}{17} = \frac{34}{10} \cdot \frac{8}{17} = \frac{2}{10} \cdot 8 = \frac{16}{10} = 1.6$$

Подставим:

$$(1.4 - 2.8) : 2.4 + 1.6 = -1.4 : 2.4 + 1.6 $$

$$-1.4 : 2.4 = - \frac{14}{10} : \frac{24}{10} = - \frac{14}{10} \cdot \frac{10}{24} = - \frac{14}{24} = - \frac{7}{12} $$

$$- \frac{7}{12} + 1.6 = - \frac{7}{12} + \frac{16}{10} = - \frac{7}{12} + \frac{8}{5} = \frac{-35 + 96}{60} = \frac{61}{60}$$

Итого:

$$ \frac{61}{60} = 1 \frac{1}{60} $$