As you can see from what I’ve drawn, 12 divided by -2 will give us -6 (12/-2=-6).
Now, ask yourself this:
3 multiplied by what makes - 6? (You have to divide) so, - 6/3= - 2. The answer is 2. So one number must be 2.
Now, what times what makes 2? 1 x 2. Since we already have 2, we just have to add 1. So the last number will be 1.