Answer: $20
Explanation:
From the question, we are informed that John Smith has a past due balance of $80 on his account and out of the $80 paid, 25% will be given as commission.
Therefore, the total commission received from John's payment will be:
= 25% × $80
= 25/100 × $80
= 0.25 × $80
= $20
The commission is $20