I would love to understand how to solve this problem: A waterpark opens up and charges $30 for admission.  Kids' tickets are half price.  If a group of people brings a soda, they can get 20% off the total price of admission.  Janet gets tickets for 10 people and 4 of them are children.  She buys a soda for $5 to take advantage of the discount for her group.  How much did she pay for everything?
Can you explain?