I don’t know I would look it up
Answer:
The greatest common factor (GCF) of a set of numbers is the largest factor that all the numbers share. Simplified expression is an expression that has been condensed and shortened, so that all the like terms have been combined.
I believe it is the introduction which should be relatively brief. You shouldn't prolong it too much, because the emphasis should be put on the main part of your speech, and not so much on the introduction.