3) (m⁻⁴/(10n⁵k²))⁻² : (5m²n³k)³ = (10n⁵k²/m⁻⁴)² · (5m²n³k)⁻³
= 10² · n¹⁰k⁴m⁸ · 5⁻³ · m⁻⁶n⁻⁹k⁻³ = 100/125 · m⁽⁸⁻⁶⁾n⁽¹⁰⁻⁹⁾k⁽⁴⁻³⁾ = 4m²nk/5
4) (9c⁵/(a³b⁻²))⁻² : (a²b⁻³/(6c⁴))³ = (a³b⁻²/(9c⁵))² · (6c⁴/(a²b⁻³))³ =
= (a⁶b⁻⁹/(9²c¹⁰)) · (6³c¹²/(a⁶b⁻⁹)) = 1/81 · a⁶b⁻⁹c⁻¹⁰ · 216c¹²a⁻⁶b⁹ = 8/3 · a⁽⁶⁻⁶⁾b⁽⁹⁻⁹⁾c⁽¹²⁻¹⁰⁾ = 8c²/3