A truck traveling from A to B will not arrive at B on time if it travels at the original speed. If you increase the speed (1/5), you can arrive 1 hour earlier than the original time; if you drive 120 kilometers at the original speed, and then increase the speed (1/4), you can arrive 40 minutes earlier. So what is the distance in kilometers between A and B?
一辆货车从甲地开往乙地，如果按原速度行驶，将不能准时到达乙地．如果把车速提高(1/5)，可以比原定时间早1小时到达；如果以原速行驶120千米后，再将速度提高(1/4)，则可提前40分钟到达．那么甲、乙两地间的距离是多少千米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 / (6/5)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">1 / (5/4)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/3) / (1/5)</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">6 - (10/3)</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">120 / (8/3)</gadget>
<output>45</output>

<gadget id="calculator">45 * 6</gadget>
<output>270</output>

<result>270</result>