Schweser Book 3 - Reading 29 # of contracts to hedge formula question

a little help please! page 100 concept checkers 9 and 10 where you are determining the number of contracts to buy / sell, the numerator in the formula for #9 is -487,500 and the numerator in #10 is -(8.559/100) times the notional. I am not following how this could be DD(T) minus DD§ as shown in the study notes? how can the numerator be the -(current dollar duration)…this is driving me crazy thanks for any help