The main road of China Optics Valley in Wuhan - Guanshan Road has a total length of 3.5 kilometers. On the design drawing with a scale of 1:50000, what is the length of Guanshan Road?
武汉中国光谷的主干道--关山路全长3.5千米，在比例尺为1：50000的设计图上，关山路长是多少．
<gadget id="calculator">1 / 50_000</gadget>
<output>1/50_000 = around 0.00002</output>

<gadget id="calculator">3.5 * 100_000 * (1/50_000)</gadget>
<output>7</output>

<result>7</result>