question: How many more million Mexicans live in the United States compared to Salvadorans residing in the United States?
#1 return the  United  States  
#2 return Mexicans that live in  #1 
#3 return Salvadorans residing in  #1 
#4 return number of  #2 
#5 return number of  #3 
#6 return difference of #4 and  #5 
#7 return division of #6 and  a million