Answer:
26% or 10/39
Explanation:
Since box A has 5 dark chocolates and 10 milk chocolates, there are 15 chocolates in all. Box B has 24 chocolates in total (12 milk, 12 dark). So there is a total of 39 chocolates in all.
There are 10 milk chocolates in Box A, so the probability of choosing any one milk chocolate out of the total 39 is 10/39 or in percentage, 26%.