question: How many more games did the Houston Astros win in 1977 than in 1975?
#1 return Houston Astros 
#2 return games that #1 win 
#3 return #2 in  1977 
#4 return #2 in  1975 
#5 return number of  #3 
#6 return number of  #4 
#7 return difference of #5 and  #6