Guests
30
Drinks each, all night
4
Times you can wash a load
0
Glasses per load
Kinds of drink on offer (fizz, wine, water...)
1
2
3
Fresh glass every drink
0
New glass per kind of drink
0
One marked glass each
0
in a hand at the peak
waiting, spare or dirty
Rule behind it: fresh = guests x drinks, minus washed glasses; per kind = guests x kinds of drink, minus washed; marked = guests x 1.2. The fresh and per-kind counts never drop below one glass per guest, and get a 10% cushion.