Your question is Coin Flip: Stop at Positive Expectation. 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).
You are offered a game where you flip a fair coin. Every time it comes up heads, you win $1 and can choose to continue or stop. Every tails loses $1. When would you stop?