№1. Вычислите: а)$$2\frac{1}{4}+1\frac{1}{5}$$

a) $$2\frac{1}{4}+1\frac{1}{5} = \frac{9}{4} + \frac{6}{5} = \frac{9 \cdot 5 + 6 \cdot 4}{20} = \frac{45 + 24}{20} = \frac{69}{20} = 3\frac{9}{20}$$

Ответ: $$3\frac{9}{20}$$