The total length of a bridge is 240 meters, and a lamp is installed every 30 meters from one end of the bridge to the other, and is installed on both sides. How many street lamps are installed in total?
一座大桥全长是240米，从桥的一头到另一头每隔30米安装一盏灯，两边都安装，一共安装了多少盏路灯？
<gadget id="calculator">240 / 30</gadget>
<output>8</output>

<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<gadget id="calculator">9 * 2</gadget>
<output>18</output>

<result>18</result>