A rectangular playground is drawn on paper with a scale of 1:8000. The perimeter of the playground is measured to be 20 cm, and the ratio of length to width is 5:3. What is the length of the playground in meters?
一个长方形操场用1：8000的比例尺画在纸上，量得这个操场的图上周长是20厘米，且长和宽的比5：3，这个操场的长是多少米？
<gadget id="calculator">1 / 8_000</gadget>
<output>1/8_000 = around 0.000125</output>

<gadget id="calculator">20 / (1/8_000) / 100 / 2</gadget>
<output>800</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">800 * (5/8)</gadget>
<output>500</output>

<result>500</result>