2. Вычислите: 1) 3 * 2/13; 2) 12 * 5/6; 3) 7 * 15/28; 4) 10/27 * 18.

Решение:

1. \( 3 \cdot \frac{2}{13} = \frac{3 \cdot 2}{13} = \frac{6}{13} \)
2. \( 12 \cdot \frac{5}{6} = \frac{12 \cdot 5}{6} = 2 \cdot 5 = 10 \)
3. \( 7 \cdot \frac{15}{28} = \frac{7 \cdot 15}{28} = \frac{1 \cdot 15}{4} = \frac{15}{4} \)
4. \( \frac{10}{27} \cdot 18 = \frac{10 \cdot 18}{27} = \frac{10 \cdot 2}{3} = \frac{20}{3} \)

Ответ: 1) \( \frac{6}{13} \); 2) \( 10 \); 3) \( \frac{15}{4} \); 4) \( \frac{20}{3} \).