If the prices increase, the demand decreases. If the prices decrease, the demand increases. For example, a new pizza place just opened up near me and their pizza is free for the opening day (today). The place is completely packed because of the low prices, well no prices I guess. But if the pizza were to suddenly get really expensive not as many people will want it because it costs more. I think you get it now so I'll stop but anyways I hope I helped lol