How many years after Nashua split into Nashua and Nashville did they rejoin and become the City of Nashua?
return Nashua  split into Nashua   and  Nashville ;return they rejoin and  become the  City of Nashua  ;return when  was  #1 ;return when  was  #2 ;return difference of #4 and  #3 in  years
['select', 'select', 'project', 'project', 'arithmetic']