purple objects plus rose objects minus cylinders equals ?
return purple objects ;return rose objects ;return cylinders ;return number of  #1 ;return number of  #2 ;return number of  #3 ;return sum of #4 and  #5 ;return difference of #7 and  #6
['select', 'select', 'select', 'aggregate', 'aggregate', 'aggregate', 'arithmetic', 'arithmetic']