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? It's not C10; 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

For this case we have the following equation:
 y = 10x + 15
 The intersection with the y axis occurs when x = 0.
 Evaluating we have:
 y = 10 (0) + 15
 y = 0 + 15
 y = 15
 The intersection with the y axis is 15 and represents the inscription in the gym.
 Answer:
 15; it represents the one-time sign-up fee