Решение:

1. а) $$\frac{4}{33} \cdot \frac{11}{19} = \frac{4 \cdot 11}{33 \cdot 19} = \frac{4 \cdot 1}{3 \cdot 19} = \frac{4}{57}$$

2. б) $$\frac{3}{22} \cdot \frac{22}{3} = \frac{3 \cdot 22}{22 \cdot 3} = 1$$

3. в) $$\frac{4}{9} \cdot 2 \frac{1}{4} = \frac{4}{9} \cdot \frac{9}{4} = \frac{4 \cdot 9}{9 \cdot 4} = 1$$

4. г) $$1 \frac{1}{5} \cdot 2 \frac{5}{6} = \frac{6}{5} \cdot \frac{17}{6} = \frac{6 \cdot 17}{5 \cdot 6} = \frac{17}{5} = 3 \frac{2}{5}$$