Respuesta :

Answer:

8.

Step-by-step explanation:

multiples of 3 for every shape.

answer: 7 sides

step by step:
first 3 have 3 sides (3 shapes)
second set of 3 have 4 sides (6 shapes)
the next set has 5 (9 shapes)
the next set has 6 (12 shapes)
the next set has 7 (the 13th shape would be in this set)
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