The distance between every two street lights is 40 meters, so how many meters is the distance between the first street light and the ninth street light?
每两盏路灯之间的距离都是40米，那么第1个路灯与第9个路灯之间相距多少米．
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">8 * 40</gadget>
<output>320</output>

<result>320</result>