Because the average value of these five numbers is 25, we can get that their sum is 5*25= 125.

Because the average value of the first three numbers is 28, we can get that their sum is 28*3=84.

Because the average value of the last three numbers is 20, we can get that their sum is 20*3=60.

Because a * * * has five numbers, and the sum of the five numbers is 125. The sum of the first three numbers plus the last three numbers is 84+60= 144.

Then the third number is calculated twice and we can get that the third number is144-125 =19.

The answer to this question is 9.

The following is the writing process:

5*25= 125

(28*3+20*3)- 125= 19

A: The middle number is 19.