62. Упростите выражение: 1) \(\frac{7}{8}p\cdot\frac{4}{9}k\); 2) \(1\frac{5}{7}x\cdot\frac{5}{12}y\); 3) \(2\frac{5}{8}mn\).

1. \[\frac{7}{8}p\cdot\frac{4}{9}k=\frac{7\cdot4}{8\cdot9}pk=\frac{7}{18}pk.\]
2. \[1\frac{5}{7}x\cdot\frac{5}{12}y=\frac{12}{7}x\cdot\frac{5}{12}y=\frac{5}{7}xy.\]
3. \[2\frac{5}{8}mn=\frac{21}{8}mn.\]

Ответ: 1) \(\frac{7}{18}pk\); 2) \(\frac{5}{7}xy\); 3) \(\frac{21}{8}mn\).