street is 360 meters long. There used to be street lamps installed every 10 meters (both ends) on the side of the street. Now, in order to save electricity, it is changed to one every 15 meters. How many street lamp poles do not need to be moved during the installation process?
一条街道长360米，原来在街道一旁每隔10米装有一盏路灯(两头都有)，现在为了节省电能要改为每15米一盏，安装过程中有多少根路灯杆不需要移动？
<gadget id="calculator">360 / 30</gadget>
<output>12</output>

<gadget id="calculator">12 + 1</gadget>
<output>13</output>

<result>13</result>