3\frac{3}{4} + \frac{1}{5} \cdot 1.25 = \frac{15}{4} + \frac{1}{5} \cdot \frac{125}{100} = \frac{15}{4} + \frac{1}{5} \cdot \frac{5}{4} = \frac{15}{4} + \frac{5}{20} = \frac{15}{4} + \frac{1}{4} = \frac{16}{4} = 4
Ответ: 4