Math Riddles

Question: Nathan has math 4 times a week. If he has math 8:00 Monday, 9:20 on Tuesday, 10:40 on Wednesday, and 1:20 on Friday, when does Nathan have math on Thursday?

Question: Which triangle will have a larger perimeter : 3,4,5 or 3,4,7 ?

Question: what are the next two letters in this sequence: A, E, F, H, I, K, L, M,

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

Question: When I was 2 years old, my brother was half my age. Now I am 100 years old, how old is my brother?