Explanation:
It is given than Paul is older than Bill.
Let age of Bill= x years, as x is a natural number.
Then, age of Paul = (x + a) Years, where a is any natural number.
And, Fred is younger than Bill.
So, age of Fred= x - k, where k is any natural number.
So, if we arrange the ages of Fred, Bill and Paul, their ages would be
Fred < Bill < Paul
x-k < x < x+a
Hence, we can say that , Paul is eldest, and Fred is smallest member between three.