addressing individuals' common ethical problems, How can we address the ethical problem in this case?

This case is about the Conflict of Interest Problem,

Your daughter is applying to a prestigious university. Since admission to the school is difficult, your daughter has planned the process carefully. She has consistently achieved high marks, taken preparatory courses for entrance exams, and has participated in various extracurricular activities. When you tell one of your best customers about her activities, he offers to write her a letter of recommendation. He's an alumnus of the school and is one of its most active fund raisers. Although he's a customer, you also regularly play golf together and your families have socialized together on occasion.