If the diagram is this
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https://media.glynlyon.com/g_geo_2013/3/page69a.gif
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Then it would go like this
|dw:1392274742487:dw|
|dw:1392274778511:dw|
|dw:1392274826374:dw|
|dw:1392274862633:dw|
The answer would be 72