Math Quiz Scores

Question: Bobby's teacher gave him a math quiz. Every time he got an answer right, points would be taken away, so whoever had the most points, got the most questions wrong. Bobby's score was the highest, yet he still got the most questions correct out of the class. How is this possible?

Question: If 4+5=24 7+2=21 9+6=63 6+7=?

Question: Leap Year is every 4 years. True or False ?

Question: When is 99 more than 100?

Question: What are the next two letters in the following series and why? WATNTLITFS__

Question: In a house of Kardak's family each brother have a sisters as double as their brothers and each sister have brothers as same as their sister. How many brothers and sisters in Kardak's family ?