请教精算专业高手一个问题 平常人勿进

under a stop-loss insurance arrangement,  the insurance amount paid is 80% of the excess of aggregate claims above 20, 
subject to a maximum payment of 5. 
All claim amounts are non-negative integers. you are given: Deductible: 16       20        24         25        26      27
                                         Net stop-loss premium: 3.89    3.33    2.84     2.75    2.69    2.65

  Determine the expected amount paid by the insurer

唉，惭愧啊，明知是那部分内容，但不看书就是想不起来，惭愧，惭愧。自己看看loss model 第五章吧，哥是不行啦

谢谢