Unusual math question?

<li>On the number line above, the tick marks are equally spaced. Which of the lettered points represents y?</li>

<p>(the -'s represent spaces, the l's represent tick marks, and the letters represent specific tick marks)</p>

<p>A - l - l - B - l - C - l - l - D - l - E </p>

<p>x is under the 'l' right before B
x+y is under the 'l' between B and C
x+y/2 is under the 'l' immediately after the C</p>

<p>A. A
B. B
C. C
D. D
E. E</p>

<p>The answer to this question was kinda lost (really old answer guide from some tests my cousin gave me), so I can't really confirm if any one explanation/answer is correct, but could you guys take a crack at it?</p>


<p>The answer is E. </p>

<p>X+Y/2 means that this point, is the average of the two points X and Y, because it is their sum over their number (2). That means, X is equally distanced from this point as Y is. Since X is located four tick marks to the left of X+Y/2, therefore, Y should in turn also be placed four tick marks to the right side of X+Y/2, placing it at the point lettered E.</p>