-200 GCf
________
2x100
4x50
8x-25
10x-20
20x-10
40x -5
-2x100
none of these give me a sum of 30. Am I doing this equation wrong?
Could someone help me?

The GCF of 10 and 20 is 10. But, what does the GCF of anything have to do with factoring. Can you provide a textbook descroption so I can track this down?

In this particular problem, you may wish to simplify your life SUBSTANTIALLY by first factoring out the GCF of the three terms.

I will be more clear in any more questions. I really feel stupid for doing that! I am so happy to have found this site to help me when I get in a stump. THANK YOU SO MUCH!