Carlota likes playing games at the local arcade. She has 15 credits to spend, and wants to spend it all playing Accuracy Ball (which costs 1 credit per round) or Dance Fever (which costs 2 credits per round). In how many ways can Carlota spend all 15 credits at the arcade, if she wants to play at least three rounds of each game? (The order in which Carlota plays games matters: Playing Accuracy Ball, then Dance Fever is different from playing Dance Fever, then Accuracy Ball.)
Honestly no idea on how to start this.