85% of the total length of a section of elevated highway has been built in a certain city, and 4.5 kilometers remain to be repaired. How many kilometers is this elevated highway?
某市修建一段高架公路，已经修了全长的85%，还剩4.5千米没有修，这条高架公路长多少千米？
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">1 - (17/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">4.5 / (3/20)</gadget>
<output>30</output>

<result>30</result>