30% of the total length of a road has been repaired, and there is still 60 kilometers away from the midpoint. How many kilometers is the total length of this road?
一条公路修了全长的30%，离中点还有60千米，这条公路全长多少千米？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(1/2) - (3/10)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">60 / (1/5)</gadget>
<output>300</output>

<result>300</result>