Respuesta :

20: 1,2,4,5,10,20
28: 1,2,4,7,14,28

Answer:

4

Step-by-step explanation:

The factors of 20 are: 1, 2, 4, 5, 10, 20

The factors of 28 are: 1, 2, 4, 7, 14, 28

Then the greatest common factor is 4.