A train travels 30% of the way at a speed of 60 kilometers per hour, and there are still 120 kilometers away from the midpoint. At this speed, how many hours will it take to complete the journey?
一列火车以60千米的时速行驶到全程的30%后，离中点还有120千米，照这样的速度，行完全程需要多少小时？
<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">120 / (1/5) / 60</gadget>
<output>10</output>

<result>10</result>