hmm, in a restaurant you can get Schnitzel with french fries for ~ 10€ fries alone may cost something around 2€.
So we can ssume a Schnitzel alone has a value of ~8€
a Beer costs something around 1,5€ so...
3 Schnitzel ~ 24€
21 Beer ~ 31,5
EDIT but as you usually won't eat a Schnitzel without...