well this is as far as i got...
Level 1 res, 0% back. Wit does not matter here.
Level 2 res, 20% back. 35 wit needed to get a 40% res, but this is impossible.
Level 3 res, 30% back. 31 wit needed to get a 50% res.
30 wit will get you a 48.9% res.
Level 4 res, 40% back. 29 wit needed to get a 60% res.
28 wit will give a 59.2% res
Level 5 res, 50% back. 27 wit needed to get a 70% res.
Level 6 res, 55% back. 27 wit needed to get a 75% res.
Level 7 res, 60% back. 26 wit needed to get a 80% res.
Level 8 res, 65% back. 26 wit needed to get a 85% res.
Level 9 res, 70% back. 26 wit needed to get a 90% res.
25 wit will give a 89.6% res
any ideas braniac?