My suggestion would be, ask your teacher. Your problem might be that you focus o the wrong aspect of the problem. Tell me, can you count? Why did you eliminate more words? Did you think words are like change back from a ten dollar bill? Did you think, "Just lop off the last few words; the sentence will make sense." You could have asked if you could drop twenty or more words, or twenty or a few less words, but you didn't. Do you have a tendency to break the rules and want to break the rules? Are you oppositional? Why not concentrate on what you might do to avoid such errors in the future. Maybe it is time to change your life around, for the better.