Because it takes Ying 30 minutes to get to the ball park and the game starts at 2:00, he must leave at least 30 minutes before the game which would bring us to 1:30. But Ying wants to arrive at the game 30 minutes before it starts so he would have to leave another 30 minutes earlier. So 1:30pm - 30minutes brings us to 1:00. Ying would have to leave at 1:00pm.
