Probability is dividing the number of items we're studying by the number of the whole items present in the zone we're studying
Bag A contains 8 chocolates and 16 chews, a total of 24 items. So the probability of Dave picking a chocolate is 8/24 = 1/3
Bag B contains 11 chocolates and 22 chews, a total of 33 items. So the probability of Mike picking a chocolate is 11/33 = 1/3
So both Mike And Dave have the same probability of picking a chocolate from their bags.
Hope this helps! :)