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To reproduce an old photograph, a photographer charges x dollars to mke a negative, 3x/5 dollars for each of the first 10 prints, and x/5 dollars for each prints in excess of 10 prints. If $45 is the total charge to make a negative and 20 prints from an old photograph, what is the value of x?
A.3
B.3.5
C.4
D.4.5
E.5
答案是E。
我没大看懂这题目什么意思,按照我的理解,就是前10张3x/5美元一份,超出部分是x/5美元一份,现在照相师要了20份,列式应该就是(3x/5)*10+(x/5)*(20-10)=45,算出来的x大于5,没有这个答案啊…是不是我理解错了?negative在这句话里是什么意思?什么叫a negative and 20 prints啊?
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