Install street lamps on both sides of a street with a total length of 3 kilometers (both ends should also be installed), one every 50 meters. How many street lights will be installed in total?
在一条全长3千米的街道两旁安装路灯(两端也要安装)，每隔50米安一座．一共要安装多少座路灯．
<gadget id="calculator">1_000 / 50</gadget>
<output>20</output>

<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<gadget id="calculator">60 + 1</gadget>
<output>61</output>

<gadget id="calculator">61 * 2</gadget>
<output>122</output>

<result>122</result>