Verified answer

1) 2a⁻² * 3a⁴ = 6a⁻²⁺⁴ = 6a²

2) 24a⁵ : (6a⁻³) = 4a⁵⁻⁽⁻³⁾ = 4a⁵⁺³ = 4a⁸

3) (2c⁻³)² =4c⁻⁶

4) 2(3⁻³b³)² 3b⁻⁴ = 2 * 3⁻⁶b⁶ * 3b⁻⁴ = 2 * 3⁻⁶⁺¹ *b⁶⁻⁴ = 2 * 3⁻⁵ * b² = 2/243 b²