橘子=4/3香蕉苹果=5/3香蕉1个橘子+1个苹果=4/3+5/3=3个香蕉
3个橘子等于4根香蕉 => 1个橘子等于4/3根香蕉3个苹果等于5根香蕉 => 1个苹果等于5/3根香蕉 1个橘子+1个苹果=9/3=3根香蕉
