Answer: $21,000
Explanation:
Cleaning expense is only related to the floor space occupied by the department.
If the company spend a total of $30,00 on cleaning each year.
And Department B occupies 70% of the company floor.
Therefore, the company spends 70% of their cleaning expense on department B
Hence, the cleaning expense on department B is given as;
= 70% of $30,000
= $21,000