If the sum of two adjacent sides of a parallelogram is 12 cm, what is the perimeter of the parallelogram in cm?
一个平行四边形，相邻两边的和是12厘米，这个平行四边形的周长是多少厘米．
<gadget id="calculator">12 * 2</gadget>
<output>24</output>

<result>24</result>