Solve Write a Mixed Numeral for the Answer $4 \frac{1}{2} \mathrm{~kg}$

Solve. Write a mixed numeral for the answer.
-The weight of a certain gas is $4 \frac{1}{2} \mathrm{~kg}$ per cubic meter. How many cubic meters would be occupied by $81 \mathrm{~kg}$ of the gas?

A) $20 \frac{1}{4} \mathrm{cum}$
B) $\frac{1}{18} \mathrm{cu} \mathrm{m}$
C) $3280 \frac{1}{2} \mathrm{cu} \mathrm{m}$
D) $18 \mathrm{cu} \mathrm{m}$