Hi,
I have the following table of criteria for loads on electronic ballasts:

A B C D
Ballasts total lamp feet max Max lamps Individual lamp feet
1 Unv Elec 1040-14 40 4 10
2 Unv Elec 216-12 16 2 8
3 Unv Elec 432-14 32 4 8
4 Unv Elec 848-46 48 6 8

I have setup the following set of data/parameters to yield a result (column
A, row 1,2,3or4):

Data

actual # lamps used 3 (cell AI64)
actual length of lamp 7 (cell AI65)
actual lamp feet required 21 (Cell AI66)


Parameters from data
ind lamp length limit 8 =IF(AI658,10,8)
# lamps used limit 4 =IF(AI642,4,IF(AI644,6,2))
total lamp ft limit 32
=IF(AI6616,32,IF(AI6632,40,IF(AI6640,48,16)))

Please advise how to lookup combination of three matching data points to
yield the proper Balast in column A.
Thanks