The perimeter of a rectangle is 90 decimeters, and the ratio of length to width is 5:4. What is the area of the rectangle?
一个长方形周长是90分米，长与宽的比是5：4，这个长方形的面积是多少平方分米？
<gadget id="calculator">90 / 2</gadget>
<output>45</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">45 * (5/9)</gadget>
<output>25</output>

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

<gadget id="calculator">45 * (4/9)</gadget>
<output>20</output>

<gadget id="calculator">25 * 20</gadget>
<output>500</output>

<result>500</result>