Answer:
Total cost for two pizzas = 21 dollars
Step-by-step explanation:
Price of plain pizza = 9 dollars.
Price of topping = 1 dollar
Number of pizzas ordered = 2
Price of pepperoni pizza = 9 + 1 = 10 dollars.
Price of mushroom and pepper pizza = 9 + 2 = 11 dollars.
Total cost of 2 pizzas = 10 + 11 = 21 dollars
Total cost for two pizzas = 21 dollars