Can someone explain i’m confused on how to do this my teacher can’t teach me this has no time

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.

A is a 2x3 Matrix while B is a 2x2 Matrix. Matrix A has 3 columns while Matrix B has 2 rows. The matrices can't be multiplied since the number of columns of the A is not equal to the number of rows of B. 

So, the answer is D) No Solution