Connor is playing a card game called At Face Value. At the end of each round, players earn positive points for their remaining number cards but negative points for their face cards. They are playing 4 rounds. At the end of round 1, Connor earns –15 points. At the end of round 2, he earns –6 points. At the end of round 3, he earns 7 points. How many points must Connor earn in round 4 to come out with a positive number of points?