the answer is 68
think about it. first add 34 plus 16. = 50.
Therefore for every fifty he throws, he will complete 34, and he will lose 16.
Now add this logic to 100. 34 + 34 = 68. (because 100/2 is 50. for every 50 it will represent 34.) If you want to extend the problem you could also answer for how many he will lose.
16 + 16 = 32.
(50 + 50 = 100) again for every 50 he will lose 16.
hope this helps.