Workers from the Urban Planning Department installed street lights on both sides of a 1.4-kilometer-long street, one every 20 meters. How many street lights were installed from the beginning to the end?
城市规化处的工人给一条1.4千米长的街道两旁安装路灯，每隔20米安一盏，从头到尾一共安装了多少盏路灯？
<gadget id="calculator">1_000 / 20</gadget>
<output>50</output>

<gadget id="calculator">1.4 * 50</gadget>
<output>70</output>

<gadget id="calculator">70 + 1</gadget>
<output>71</output>

<gadget id="calculator">71 * 2</gadget>
<output>142</output>

<result>142</result>