We are told that one dance class costs $15. Therefore, for x classes, Hailey will pay
There is also an administrative fee of $25, which will be paid just once. Thus, to calculate the total cost y of taking x dance lessons, we should add this value to 15x. Now, we can write the rule that describes this situation.
Now, let's calculate the cost of 5 lessons using our rule. We can then see if the cost is less than $100 or not. This is done by substituting 5 for x.