From the title, we can know that 80X+65Y=72(X+Y).

80X+65Y=72X+72y

8x=7y

x/y=7/8

So the ratio of male to female is 7:8.

Because the number of people is at least 1, and they are all natural numbers, such as 1, 2, 3, 4 and so on.

So the total number of men and women is at least 15, then 30, 45, 60 and so on.

Prove that the total number of men and women is a multiple of 15.

Between 35 and 60, only 45 is a multiple of 15.

Solution: b