Alice gets a first chance then he can choose any number from (1-15) but betty will choose from numbers except from which on addition with previously chosen with alice's digit,we will get 16.
suppose,sequence is like this:
alice betty
9 2
8 10
11 3
4 7
5 6
12 13
14 15
1 //alice has no other coice but to choose 1,so (15+1) = 16,hence alice looses and betty wins
BUT now consider this scenario:-
Alice Betty
10 3
7 4
11 6
12 13
15 5
1 14
9 2
8 8 //here beety has no other coice but to choose 8 and hence,it makes up 16.and in this case alice wins
so,how can we decide that whether alice will win or betty wil win??