Actually, I don't really understand how are calculated damages, if you just take the given informations then each LF3 is dealing up to 150 damages but, first of all, damages are never the same, so if I consider you have 15 LF3 (level 1) et 16 on irises, it must deal :
15 x 150 = 2250
on iris : 16 x 150 = 2400 + 10% bonus damages(240) = 4890
so with 31 LF3 you must deal up to 9930 on x1 without seprom and with seprom :
4890 + 60% = 7824 for 31 LF3 lvl 1 so where is the problem ?
For 16 lvl 16 LF3, it means +6% damages so it might deal up to :
4890 + 6%(upgraded LF3) = 5183,4 + 60% (seprom) = 8293,44
Idk If I'm write or just missing something. Anyway If I'm right, you'll deal :
x1 = 8293
x2 = 16586
x3 = 24880
x4 = 33173
RSB75 = 49760