Final answer:
The score is 40-15 in favor of Juan. Juan needs to win one more point to win the game unless Nick ties the score at deuce, after which a player must win by two points.
Step-by-step explanation:
In tennis, the score for each player is not counted as 1, 2, 3, etc. Instead, the scores correspond to specific calls. When a player has scored once, it's called '15'. The second time a player scores, it's '30', and the third is '40'. With Juan having scored three times and Nick once, the score is 40-15 in favor of Juan.
Juan has the better chance to win the game at this point. For Juan to win the game, he needs to win one more point as he is already at '40'. However, if Nick scores the next point making it 40-30, Juan still needs only one more point to win the game. If Nick ties the score at '40-40', this is called 'deuce', and the game requires a player to win by two clear points.
In summary, with the score at 40-15, Juan is ahead and needs only one more point to win the game. If Nick makes a comeback and brings the score to deuce, both players would need to sequentially score two points to win the game.