Install street lights on both sides of a street with a total length of 2 kilometers, (both ends must also be installed) every 40 meters. How many street lights will be installed in total?
在一条全长2千米的街道两旁安装路灯，(两端也要安装)每隔40米安一座．一共要安装多少座路灯．
<gadget id="calculator">1_000 / 40</gadget>
<output>25</output>

<gadget id="calculator">2 * 25</gadget>
<output>50</output>

<gadget id="calculator">50 + 1</gadget>
<output>51</output>

<gadget id="calculator">51 * 2</gadget>
<output>102</output>

<result>102</result>