A pizzeria sells cheese pizzas with diameters ranging from 10 - 20 inches. The price of a 10 inch pizza is \$8.99. Area can be calculated using the formula $A=\pi { r }^{ 2 }$ where $r$ is the pizza radius.

The pizzeria uses a direct variation model to determine the base price of a pizza depending on its area. If the area of pizza $x$ is double that of pizza $y$ (thus requiring double the ingredients), the base price of $x$ is double the base price of $y$. To remain competitive, the pizzeria offers discounts from the base price for larger pizzas.

Calculate the base price, $P$, of a 20 inch diameter pizza according to the direct variation model. The pizzeria offers a \$15.00 discount resulting in a final sale price that is $D$% of $P$. Determine an algebraic expression for $D$.

Value of P

Value of D

Value of P

Value of D

$ 17.98

Value of P

Value of D

$ 35.96

Value of P

Value of D

$ 80.82

Value of P

Value of D

$\cfrac {15}{P}\cdot100$

Value of P

Value of D

$\cfrac {P-15}{P}\cdot100$

Value of P

Value of D

$\cfrac {P-15}{15}\cdot100$