Given that the lengths of two adjacent sides of a parallelogram are 7cm and 12cm, what is its perimeter?
已知平行四边形的相邻两条边长是7cm和12cm，求它的周长是多少？
<gadget id="calculator">7 + 12</gadget>
<output>19</output>

<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<result>38</result>