Uncle Li traveled by bicycle. On the first day, he rode 19 kilometers and 420 meters, which was 500 meters less than the second day. On the third day, he rode 18 kilometers and 900 meters. How many kilometers did Uncle Li travel in three days?
李叔叔骑车旅行，第一天骑了19千米420米，比第二天少骑了500米，第三天骑了18千米900米，李叔叔三天一共行了多少千米？
<gadget id="calculator">500 / 1_000</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">19.42 + (1/2) + 19.42 + 18.9</gadget>
<output>58.24</output>

<result>58.24</result>