It isn't a complete statement, so there is no truth value. Consider the statement: The sky is blue. Simple enough to go outside or look out through what you assume to be a clean window and verify the truth of the statement. But consider The sky is. Not a statement, and you cannot assign a truth value to it. Same with your mathematical expression, which, in words says "The quantity seven times some number less two times the quantity two times the same number less seven is" Is what? No way to tell whether it is true or false.
This is exactly why your English teacher marks you down for writing a sentence fragment.
John
My calculator said it, I believe it, that settles it
