Step-by-step explanation:
d⁷ (d⁻¹)³ = d⁷ (d⁻³) [using the laws of logarithm to simplify]
= d⁷ ⁺ ⁽⁻³⁾
= d⁴
It's always good to substitute in numbers to check your answer
3⁷ (3⁻¹)³ = 81 = 3⁴
