How can you calculate the frequency of each allele in this population?

Some info might be missing in the question, but if those are the answers to choose from, then the first one is brown alleles.

Since the 4th and 5th sentence ask for a frequency, which can only be answered with a number lesser than 1, they must be either 0.4 or 0.6.

Taking these numbers into consideration and dividing all numbers one by another, the only number that makes sense mathematically for the 3rd blank is 20, because 8/20= 0.4 which is one of the two frequencies (and the only of the two that can be obtained by dividing one of the numbers given by another of the possible answers).

This means the number of brown alleles must be 8 (2nd blank) because no other number given would fit in and give 0.6

This means that the 4th blank must be 0.4 and the 5th blank must be 0.6

Thank you so much! I see where the numbers came form now.