<h2>
Answer:</h2>
The cost of 2 pizza is:
$ 21
<h2>
Step-by-step explanation:</h2>
It is given that:
A plain pizza costs $9.
Each topping costs $1.
Also, a group of friends ordered two pizzas.
This means that the cost of two plain pizzas will be: $ (9×2)
i.e.
Cost of two plain pizzas will be: $ 18
Also, there are three toppings in total.
(Pepperoni,mushrooms and green peppers)
This means that cost of three toppings= $ (1×3)
i.e.
Cost of three toppings=$ 3
Hence, Total cost of 2 pizza=Cost of 2 plain pizza+Cost of 3 toppings
i.e.
Total cost of 2 pizza=$ 18+$ 3
i.e.
Total cost of 2 pizza=$ 21
