Calc for performance status, 4 levels with 3 criteria

[b.hunt 0]

Hi there I have:

3 fields which relate to team performance criteria:  ServiceTakings, RequestRate, and RebookPercent.

We have 4 performance levels, team have to hit each criteria for said level to be awarded.

i.e. tier 1 request rate = 0-39%, tier 2 request rate = 40-60%, tier 3 61-75% and tier 4 = 75%+

tier 1 ServiceTakings = 0-£4400, tier 2 = 4400-£58000, tier 3 = 5801-7000, tier 4 = 7001+

Team could be working at level 4 for serviceTakings, and level 3 for Request and 2 for rebook, in this instance the would only be awarded level 2 overall

How can I set up a simple calculation to tell me which tier the team member is in? Hope someone can give me some help, kind regards

 

(Edit: I'm using Filemaker Pro 12)

Edited May 22 by b.hunt