3. Сократите: 1) (15·17 − 15·6)/(15·17 + 15·6); 2) (81·17 − 15·81)/(81·17 + 81·4).

1) \(\frac{15\cdot17-15\cdot6}{15\cdot17+15\cdot6}=\frac{15(17-6)}{15(17+6)}=\frac{11}{23}\).

2) \(\frac{81\cdot17-15\cdot81}{81\cdot17+81\cdot4}=\frac{81(17-15)}{81(17+4)}=\frac{2}{21}\).

Ответ: 1) \(\frac{11}{23}\); 2) \(\frac{2}{21}\).