1. 8⁻²-(8/9)⁻¹=1/8²-9/8=(1/64)-(9/8)=(1-9*8)/64=(1-72)/64=-71/64.
2. 8⁻⁶:8⁻⁷=8⁽⁻⁶⁻⁽⁻⁷⁾⁾=8⁽⁻⁶⁺⁷⁾=8¹=8.
3. (-10)⁵*(5²)⁻²=(-2*5)⁵*5²*⁽⁻²⁾=-2⁵*5⁵*5⁻⁴=-32*5⁵⁻⁴=-32*5=-160.
4. (-1/6)⁻²; 3⁻³; (-15)⁵.
5. 9⁻⁵*27⁻³/3⁻¹⁹=(3²)⁻⁵*(3³)⁻³/3⁻¹⁹=3⁻¹⁰*3⁻⁹/3⁻¹⁹=3⁻¹⁹/3⁻¹⁹=1.