求助！prep2-ds-11

pangpangshin

What is the value of the positive integer m ?


(1)When m is divided by 6, the remainder is 3.


(2)When 15 is divided by m, the remainder is 6.

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给的答案如下！
【答案】B

【思路】

(1) m=6k+3 (k是整數),m有太多可能,不充分

(2) 15=m+6, m = 9,充分

可是我怎么觉得由（2）得出的应该是 15=cm+6这样的话，综合1和2 才能选出来，应该选C吧！
请大牛们指点~

wahabirds

When 15 is divided by m, the remainder is 6.

Therefore, m is bigger than 6 and smaller than 15.  m is selected from 7, 8, 9, 10, 11, 12,13,14.   Only 9 fulfills the requirement.

pangpangshin

哦，明白了！谢谢！