Calculating Commissions

Hello, having some trouble figuring out how to do this calculation. Everything is setup.

Two variables I need to take into account: Quota and Current Bookings.

To calculate commission, we have 3 tiers, 0-60% of quota, 60-100% and >100%

The rates are as follows
0-60% of Quota, pays out 6.5%
60-100% of Quota, pays out 14%
>100% pays out 18%

Say for example, you have a quota of $100,000 and current bookings of $150,000.
0-60% of Quota ($60,000), pays out 6.5% ($3,900)
60-100% of Quota ($60,000-100,000), pays out 14% ($5,600)
>100% (>$100,000), pays out 18% ($9,000)

Also, further complicated is that if you have over 75% of quota, you get $5000 bonus, if over 100% you get $10,000.

Any help to create a formula for % of quota and % commission would be greatly appreciated. Thank you!!!

Assuming quota in in A, Bookings in B, then C would look like:
=IF(B2/A2<=0.6,0.065*B2,IF(AND(B2/A2>0.6,B2/A2<=1),IF(B2/A2>=0.75,(B2*0.14)+5000,B2*0.14),(B2*0.18)+9000))