请教陈向东模拟一17题，25题

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17.In the xy-plane ,lin k is a line that does not pass throgh the origin .which of the following statements individually provide sufficient additonal information to determime whether the shope of line K is negative ?indicate all such statements.
a.        the x-intercept of line k is twice the y-intercept of link k.
b.        the produce of the x-intercept an the y-intercept of link k is positive,
c.        link k passeds through the point (a,b)and (r,s),where (a-r)(b-s)<0
a不是不能确定么？x截距是Y截距的2倍，那么和X轴的交可以为钝角或者锐角，那么斜率不就是可正可负》
b.截距不是都是正数么？x截距是Y截距的积能说明斜率是正的吗？
25.The company at which Mark is employed has 80 employees,each of whom has a different salary. Mark's salary of $43700 is the second-highest salary in the first quartile of the 80 salaries. If the company were to hire 8 new employees at salaries that are less than the lowest of the 80 salaries, what could be Mark's salary be with respect to the quartile of the 88 salaries at the company, assuming no other changes in the salaries?
A. The  fourth-highest salary in the first quartile
B. The highest salary in the first quartile
C. The secone-lowest salary in the second quartile
D. The third-lowest salary in the second quartile
E. The fifth-lowest salary in the second q
答案是e这句话的理解 the second-highest salary in the first quartile of the 80 salaries是怎么的？
O(∩_∩)O谢谢