Answer and Explanation:
The journal entries are shown below:
On Oct 15
cash Dr $21,000
Service charge expense Dr (3% of $30,000) $9,000
To Account receivable $30,000
(being the cash is recorded)
On Oct 25
cash Dr $882
Service charge expense Dr (2% of $900) $18
To Sales $900
(being the cash is recorded)
These two entries should be recorded