The perimeter of a rectangle is 18 meters, and the ratio of length to width is 5:4. What is the area of the rectangle?
一个长方形的周长是18米，长和宽的比是5：4，这个长方形的面积是多少平方米？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

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

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

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

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

<gadget id="calculator">9 * (5/9) * 9 * (4/9)</gadget>
<output>20</output>

<result>20</result>