请问： Mata bought several pencils, if each pencil was either 23 cent pencil or 21 cent pencil, how many 23 cent pencils did Mata buy? (I) Mata bought a total of 6 pencils. (II) The total value of the pencils Mata bought was 130. 答案：Statement (II) alone is sufficient, but statement (I) alone is not sufficient. 为什么不是Both together are sufficient, but neither statement alone is not sufficient?我的考虑是：23X+21Y=130，并不可能解答出来23元的是几支铅笔的亚？请问是否我的考虑有错误？谢谢！ | 
