Total Cost of Pizzas with Promotion

A local pizza shop offers two types of pizzas: a small pizza and a large pizza. The price of a small pizza is $10 and the price of a large pizza is $15. The shop has a special promotion that offers a discount on the total cost based on the number of pizzas ordered.

The total cost $C$ for ordering $x$ small pizzas and $y$ large pizzas can be described by the piecewise function:

$$ C(x, y) = \begin{cases} 10x + 15y & \text{if } x + y \leq 5 \\ 10x + 15y - 5 & \text{if } 5 < x + y \leq 10 \\ 10x + 15y - 10 & \text{if } x + y > 10 \end{cases} $$

What will be the total cost if 3 small pizzas and 4 large pizzas are ordered?