27) (a³)⁴·a¹² / a²¹, a=5

1. Simplify the numerator: a¹²·a¹² / a²¹ = a²⁴ / a²¹.
2. Simplify using exponent rules: a²⁴⁻²¹ = a³.
3. Substitute a=5: 5³ = 125.