Letter for an adjustment Business Memo Writing Format

You were recently invited by your former educational institution to give a presentation on "International Business Practices by Canadian Entrepreneurs" to its business students. Unfortunately, you will be away that week, for work-related activities in the Bahamas. You are grateful that they asked though and are disappointed to be unable to attend. Politely refuse the invitation to give a presentation due to your work-related engagement reason. Perhaps you would be able to speak at another time in the near future.