A rectangle has a perimeter of 68 cm and a length of 20 cm, what is the area of the rectangle?
一个长方形的周长是68cm，长是20cm，这个长方形的面积是多少？
<gadget id="calculator">68 / 2</gadget>
<output>34</output>

<gadget id="calculator">34 - 20</gadget>
<output>14</output>

<gadget id="calculator">14 * 20</gadget>
<output>280</output>

<result>280</result>