You and Leon have been sitting at the same desk for years.you both had fun in class all the time,almost forgetting about studying.but Leon was an excellent student and could cope with any topic in mathematics,and you couldn't.you didn't understand math at all. you were sitting in class and indifferently looking at the numbers in the notebook, trying to solve examples.Leon nudged you, smiled,and whispered"Hey,baby,can I help you with math?"