The price of a gym membership has a one-time sign-up fee and a monthly fee. The price can be modeled by the function y = 10x + 15, where x is the number of months.
What is the y-intercept, and what does it represent? (1 point)
10; it represents the monthly fee
10; it represents the one-time sign-up fee
15; it represents the monthly fee
15; it represents the one-time sign-up fee