[tex]d^5[/tex]
Recall the Law of Exponents:
[tex]\frac{a^m}{a^n} = a^{m -n}\\[/tex]
Rewriting [tex]\frac{d^9}{d^4}\\[/tex]:
[tex]\frac{d^9}{d^4} \\ d^{9 -4} \\ d^5[/tex]