How many years after the slave trade was ended in teh Ddanish West Indies were the slaves finally emancipated?
return the  slave trade was  ended in  the Ddanish West Indies ;return the  slaves were finally emancipated ;return year of #1 ;return year of #2 ;return the  difference of #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']