A car has traveled 30% of the journey from City A to City B, and it is still 20 kilometers away from the midpoint. How many miles is the distance between A and B?
一辆汽车从甲城开往乙城，已经行了全程的30%，这时距离中点处还有20千米．甲、乙两城相距多少千米？
<gadget id="calculator">1 / 2</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">20 / (1/5)</gadget>
<output>100</output>

<result>100</result>