write a letter to reply him:
- give your opinion about your friend's business idea
- tell him weather or not you have decided to accept his offer
- and explain your reason for this decision
I hope you are doing good. Happy to receive a mail from you. Thanks for choosing me to be as your partner for your new venture. I am replying back to let you know my opinion on this.
It was a great business idea by the way, The powerpoint presentation sent by you to explain the whole point of business is crystal clear. I can imagine how it is going to run. Even though, cab companies are already a lot in our city, the unique ideas you mentioned within the document are going to be the selling points, which bring's high profits in return.
I would like to tell you an example. One of my relative recently started a food delivery company in Mumbai. He's yielding around twenty percent margin every month by applying his creative thoughts into the business.
Even though the idea is great, I am sorry to reject your offer. I have been totally involved in the hotel venture which was started last December. I am spending more than eight hours a day to visit all our newly opened restaurants in the nearby towns. With such busy schedule in a week, I cannot spend time to manage any other activity. Hope you can understand the situation. All the very best for all your new plans. Write me if you need help in any other means.