If 9 pizzas cost $180, but we want to find out how much 15 pizzas would cost.
First, you want to figure out how much each pizza cost, we know that 9 pizzas cost $180.
180 ÷ 9 = 20
$20.00 per pizza.
Now that we know that each pizza cost $20, we just have to multiply the $20.00 and 15.
20 x 15 = 300
So, 15 pizza would cost $300.00
Hope this helps. :)