Answer:
1)
The factors of 9 are: 1, 3, 9
The factors of 15 are: 1, 3, 5, 15
Then the greatest common factor is 3.
2)
The factors of 16 are: 1, 2, 4, 8, 16
The factors of 28 are: 1, 2, 4, 7, 14, 28
Then the greatest common factor is 4.
3)
The factors of 50 are: 1, 2, 5, 10, 25, 50
The factors of 75 are: 1, 3, 5, 15, 25, 75
Then the greatest common factor is 25.
