How many more slaves were there compared to white people on the island in 1791?
return the  island ;return #1 in  1791 ;return slaves on #2 ;return white people on #2 ;return number of  #3 ;return number of  #4 ;return difference of #5 and  #6
['select', 'filter', 'project', 'project', 'aggregate', 'aggregate', 'arithmetic']