Your question is Arbitrage From Option Prices. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Three options are priced at $12, $7, and $1 with strikes at 10, 20, and 30; what arbitrage opportunity exists, and what is the cash flow?