<https://gmatclub.com/forum/if-points-p-q-and-r-appear-on-a-number-line-as-shown-above-is-p-318080.html#p2471826>
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<https://gmatclub.com/forum/if-points-p-q-and-r-appear-on-a-number-line-as-shown-above-is-p-318080.html>