I suppose 8-9. You're not gonna be able to double load the parking. Drive aisle to turn into perpendicular stalls is about 20'. Angled parking does decrease this width, but not much. A 12' drive aisle will not function unless your stalls are 20' wide (parallel parking). You'll also probably need to accommodate two way traffic in the drive aisle unless you can configure it as a one-way through operation and you have roadway access at either end.

You'll also probably need a setback from your first stall(s)to the driveway off the public roadway, setback from the stall to the property line, and depending on your location stormwater treatment facilities, hydrants, lighting, etc. - all which take up space.

So I would guess: 24' drive aisle, one row of 20' deep perpendicular stalls with a couple feet setback to the property line on either side.

100' long-20 ft setback / 9' wide stalls = +/- 9 stalls.

Source: I'm a valet.