Answer:
The customer have to accept the trade at the amount of $28
Explanation:
Based on the information given we were told that the actual amount the customer paid when the customer order was filled was the amount of $28 and not the amount of $27.50 which was the purchase price given by the broker dealer, Hence based on this we can vividly say that the customer have to accept the trade at the amount of $28 which was the actual amount paid when the order was filled.
Therefore the customer will have to accept the trade at the amount of $28.