Two identical regular triangles have a perimeter of 18 decimeters. If they are assembled into a parallelogram, what is the perimeter of the parallelogram?
两个完全一样的正三角形，它们的周长都是18分米，将它拼成平行四边形，平行四边形的周长是多少．
<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<result>24</result>