62. Упростите выражение: 1) 2/3 * a * 7/12 * b; 2) 8/9 * x * 1 4/5 * y; 3) 5m * 2 6/11 * n * 2 5/14 * k.

1) \[\frac{2}{3} a \cdot \frac{7}{12} b = \frac{2 \cdot 7}{3 \cdot 12} ab = \frac{14}{36} ab = \frac{7}{18} ab\] 2) \[\frac{8}{9} x \cdot 1\frac{4}{5} y = \frac{8}{9}x \cdot \frac{9}{5}y = \frac{8 \cdot 9}{9 \cdot 5}xy = \frac{8}{5}xy = 1\frac{3}{5}xy\] 3) \[5m \cdot 2\frac{6}{11}n \cdot 2\frac{5}{14}k = 5m \cdot \frac{28}{11}n \cdot \frac{33}{14}k = \frac{5 \cdot 28 \cdot 33}{11 \cdot 14}mnk = \frac{5 \cdot 2 \cdot 14 \cdot 3 \cdot 11}{11 \cdot 14}mnk = 5 \cdot 2 \cdot 3 mnk = 30mnk\] Ответ: 1) 7/18 ab; 2) 1 3/5 xy; 3) 30 mnk