Answer: Restaurant's monthly breakeven point in sales is $31333.
Step-by-step explanation:
Since we have given that
Number of guests = 20,000
Average sales = $120,000
Contribution margin per guest = $1.50
Let the number of sales be 'x'.
Cost per sales would be

Margin contributed by 2000 guests would be

So, Revenue function would be

Fixed monthly cost = $ 50,000
Variable cost for 20000 guests = $90000
So, Variable cost per sale would be

So, Cost function would be

Breakeven point would be
Cost function = Revenue function

Hence, Restaurant's monthly breakeven point in sales is $31333.