To build a road, the full length (3/4) has been built, which is exactly 30 kilometers. How many kilometers is the total length of this road?
修一条公路，已经修了全长的(3/4)，正好是30千米，这条公路全长多少千米？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">30 / (3/4)</gadget>
<output>40</output>

<result>40</result>