Last year the annual premium on a certain hospitalization insurance policy was $408, and the policy paid 80% of any hospital expenses incurred. If the amount paid by the insurance policy last year was equal to the annual premium plus the amount of hospital expenses not paid by the policy, what was the total amount of hospital expenses last year?
几个月前做过的题 当时错了 现在又忘记是怎么回事了
这里的premium应该是作为额外费用来理解吧
我的计算公式是 408+0.2x=x
x算出来就应该是insurance，再加上408的premium，得出total expenses... | 
