A rectangle has a perimeter of 60 cm and its length is twice its width. Find the area of this rectangle.
一个长方形的周长是60厘米，长是宽的2倍．求这个长方形的面积．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">30 * (2/3)</gadget>
<output>20</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">30 * (1/3)</gadget>
<output>10</output>

<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<result>200</result>