Question

An aerobics class is being offered in the gym. The registration fee is $15 and the cost for each class is $10.

Answer 1

If you're asking for a equation/function:

f(x)=10x+15 or

y=10x+15

Explanation:

We don't know the number of classes she will take, so represent that number with x, the cost of the classes, plus the registration fee would be 10x, the cost of each class and how many class she take, with 15, the registration fee.