C= total $ cost
n= number of pizzas purchased
x= $ cost per pizza
C= x * n
C= xn
If you know the cost per pizza and the number of pizzas purchased, plug those numbers in the equation above to find the total cost.
EXAMPLE: If each pizza cost $10 and 5 were purchased, the equation would be: C= ($10)(5)= $50 total
ANSWER: C= xn
Hope this helps! :)