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On Alison's Triangles there is a very simple solution. Becuase on each of the base lines of the triangles are wirth 4 units, you do 23 times 4 to get the furthest vertex, minus 4 to get the closest vertex and add 2 to get to the centre and add 5 going upwards,(since the triangles all go upwards 5 and along 2 to get the highest vertex.)