What are the average ages of losers and winners across matches?
return matches ;return losers of  #1 ;return winners of  #1 ;return ages of  #2 ;return ages of  #3 ;return average of  #4 ;return average of  #5 ;return #6 ,  #7
['select', 'project', 'project', 'project', 'project', 'aggregate', 'aggregate', 'union']