I am stomped on the following question

Which is greater judging from the number line if $\rm JL = KM.$

a) $\rm JK$

b) $\rm LM$

(Answer : Both are the same)

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I would like to know how they concluded both are same ?

  • 3
    $\begingroup$ $L-J=M-K\Rightarrow L-M=-K+J\Rightarrow M-L=K-J$. $\endgroup$ – David Mitra Aug 2 '12 at 14:57
  • $\begingroup$ @DavidMitra . That makes sense. So on a number line $JL$ can be written as L-J right ? $\endgroup$ – MistyD Aug 2 '12 at 15:05
  • 2
    $\begingroup$ Yes, $5-3 = 2$ as in: $-\stackrel{3}{|}-\stackrel{4}{|}-\stackrel{5}{|}-.$ $\endgroup$ – user2468 Aug 2 '12 at 15:07


We have $\rm JL = JK + KL$ and $\rm KM = KL + LM.$ (Exercise: why does these equalities hold?). Equate, simplify, and conclude.


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