I think you are being asked to find out how much each person is to pay. (Is the bill really $4500 or should it be $45.00?)
You should first add the tip of 15% of the bill. Thus, find 15% of the bill and add it to the bill to determine what you owe before the discount. I think you should tip the server with 15% of the entire bill not the discounted bill.
Next find 10% of of the bill (either $4500 or $45.00, whichever is correct) and subtract it from what you owe.
Finally divide by 3 to determine what each of the 3 people need to contribute.