GRE考试

【单选题】


网考网参考答案：D
网考网解析：
If x and y represent the number of 5-cent stamps and 7-cent stamps, respectively, that Dalia used, then 5x + 7y = 75. There are infinitely many solutions to this equation, but there are only two solutions in which x and y are both positive integers: y = 10 and x = 1 or y = 5 and x = 8. Neither column is always greater, and the two columns are not always equal (D). document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>