question: How many field goals between 20 and 30 yards were kicked?
#1 return field goals 
#2 return yards of #1 
#3 return #1 where #2 is at least 20 
#4 return #1 where #2 is at most 30 
#5 return #1 in  both #3 and  #4 
#6 return number of  #5