question: How many more percentage was the graduation class was employed by by nine months after graduation than secured positions in one nations largest firms?
#1 return the  graduation  class 
#2 return #1 that was  employed by nine months after graduation 
#3 return #1 that secured positions in  one of the  nations largest firms 
#4 return percentage of #2 
#5 return percentage of #3 
#6 return the  difference of #4 and  #5