The lengths of a pair of adjacent sides of a parallelogram are 20 cm and 15 cm respectively, what is its perimeter in cm?
一个平行四边形的一组邻边的长分别是20厘米和15厘米，它的周长是多少厘米？
<gadget id="calculator">20 + 15</gadget>
<output>35</output>

<gadget id="calculator">35 * 2</gadget>
<output>70</output>

<result>70</result>