3. Упростите: 1) (13x⁻⁶/y⁻⁶) · (y/(65x⁻⁵)); 2) (21a⁻⁴/(15b⁶)) · (5b⁻⁶/(28a⁻⁸)).

1. \(\frac{13x^{-6}}{y^{-6}}\cdot\frac{y}{65x^{-5}}=\frac{13}{65}x^{-6-(-5)}y^{6+1}=\frac{1}{5}x^{-1}y^7=\frac{y^7}{5x}\).
2. \(\frac{21a^{-4}}{15b^6}\cdot\frac{5b^{-6}}{28a^{-8}}=\frac{21\cdot5}{15\cdot28}a^{-4-(-8)}b^{-6-6}=\frac{a^4}{4b^{12}}\).

Ответ: 1) \(\frac{y^7}{5x}\); 2) \(\frac{a^4}{4b^{12}}\).