A gaming platform offers two plans. The NPC plan has a $15 registration fee, and costs $10/month after that. The Hero plan has a $75 registration fee, and costs $5/month after that.

Which plan is cheaper if you're only going to use your account for a few months? Which plan is cheaper if you're going to use it for a few years? If two people choose different plans, at what point will they both have paid the same total amount?