Which of the following is not a positive multiple of 9+3? a.3 b.12 c.24 d.48 e.60

9 + 3 = 12, a multiple of 12 is B, C, D, and E, but not A, A "3" is a factor.

Well, we know that 9+3=12. 

Meaning that we are looking for multiples of 12. These are numbers you get when multiplying 12 to any number.

The positive multipes here are 12, 24, 48, and 60.

Which means that A. 3  is the answer since it is not one of the multiples. You only get 3 when you are looking for factors of 12.