To build a road, 15% of the whole journey has been repaired. At this time, there are still 70 kilometers away from the midpoint. How long is this road?
修一条公路，修了全程的15%，这时距离中点还有70千米，这条公路有多长？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(1/2) - (3/20)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">70 / (7/20)</gadget>
<output>200</output>

<result>200</result>