the way you do it is by checking the letter in every term and seeing which instance has the lowest of that letter (for now pretend the regular numbers, in this case 6 24 and 12, aren't there). Once you do that you'll see that the last term has each variable (letter) to the power of one, so that will be the common factor for the letters. Next, look at the real numbers, and you see that the lowest number each can be divided by is 6. so you have 6abc. I'm tired and I think I explained it in a confusing way, so if you still have questions search up "how to find the greatest common factor in polynomials"
What divided by what equals 0? What divided by what equals 0? Specifically, what positive whole number (X) can you divide by another positive whole number (Y) to get 0? The answer is infinite.
