The uncle of the police received a report that a group of robbers committed crimes in the supermarket. When the police car arrived at the supermarket, the robbers had already fled to a bridge a minute ago. The speed is 30 kilometers per hour, so the robbers arrived at the bridge 4 minutes earlier than the police, and when the police arrived at the bridge, the robbers were already 12 kilometers away from the bridge, and asked the distance between the supermarket and the bridge.
警察叔叔接到报警，有一群劫匪在超市作案，当警车赶到超市时，劫匪已经于1分钟前逃向一座大桥，警车立即驱车追赶，但劫匪抢来的跑车的速度比警车的速度每小时快30千米，因此劫匪比警察早4分钟到大桥，而当警察到达大桥时，劫匪已经在离桥头12千米处，问超市到桥之间的距离．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">12 / (1/15)</gadget>
<output>180</output>

<gadget id="calculator">180 - 30</gadget>
<output>150</output>

<gadget id="calculator">1 / 150</gadget>
<output>1/150 = around 0.006667</output>

<gadget id="calculator">1 / 180</gadget>
<output>1/180 = around 0.005556</output>

<gadget id="calculator">(1/150) - (1/180)</gadget>
<output>1/900 = around 0.001111</output>

<gadget id="calculator">(1/20) / (1/900)</gadget>
<output>45</output>

<result>45</result>