AMC 8 1990 Problem 10
AMC8 1990 年第 10 题
数列与规律★★☆☆☆
On this monthly calendar, the date behind one of the letters is added to the date behind C. If this sum equals the sum of the dates behind A and B, then the letter is
在这张月历上，其中一个字母背后的日期与 C 背后的日期相加。如果这个和等于 A 和 B 背后日期之和，则该字母是
- A.
- B.
- C.
- D.
- E.
正确答案 · Correct Answer
A
解析 · Solution
Solution 1
Since the date behind C is 1 less than the date behind A, the date added to the date behind C should be 1 more than the date behind B, which would be the date behind .
Let the date behind C be , and be the date added to C. Then the date behind A is x+1, while the date behind B is x + 13. So (x+1)+(x+13)=x+y, and therefore y=x+14, which is the date behind .
-motorfinn, edited by j314andrews
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