3. (10%) In American football, teams take turns in offense and defense. Assume that the only way teams can score is through offense. In the overtime, the team that scores first wins the game and they keep playing until a winner comes through. There is no tie game. Suppose Team A takes the offense first against Team B, and the probability of scoring at offense is \( 50\% \) for either of the teams. What is the winning probability for Team A when they play in the overtime? What is the winning probability of Team B?