I am trying to write the code for a conference:

1 person costs $695.00
2-4 people costs $545
5-8 people costs $480
8 or more costs $395

If the company has been before they get a 15% discount and no company can have more than 16 people. The program asks that the user enters valid data.?? (error msg boxes)

Could someone show me how to do this?