[Algebra, polynomials] I'd like help with further explanation with what the image is telling me. I understand that you find the GCF of each term, but for the question I don't know why the GCF of the exponents are 3. I thought 4 would be the GCF. I don't think I learned how to find GCF properly.

As for the second image, I just have no clue on how to do it. I don't want just the answer. Anyone good with math please help :)