A rectangular vegetable field has a circumference of 72 meters and a ratio of length to width of 4:5. What is its area?
一块长方形菜地，四周的长度是72米，它的长与宽的比是4：5，它的面积多大？
<gadget id="calculator">72 / 2</gadget>
<output>36</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">36 * (5/9)</gadget>
<output>20</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">36 * (4/9)</gadget>
<output>16</output>

<gadget id="calculator">20 * 16</gadget>
<output>320</output>

<result>320</result>