I can't answer it the problem
It is always because if you have an improper fraction, the larger number is always the numerator. To get a reciprocal, you flip the fraction so that the denominator is the numerator, and vice versa. If the numerator is always bigger, and you make it the denominator, it would be proper.
We are given the data about the ratio of the number of pounds of potato-salad and the number of people that can be fed. In this case, the ratio is 3 pounds/ 15 people or 1 pound of potato salad per 5 people fed. For 200 people, 200 people* (1 pound of potato salad per 5 people) is equal to 40 pounds of potato-salad