A car travels from A to B. If the speed of the car increases by 20 kilometers per hour, the time it takes will change from 4 hours to 3 hours. How many kilometers are there between A and B?
某车从甲地驶向乙地，如果车速每小时提高20千米，那么所用时间由4小时变为3小时．甲、乙两地相距多少千米？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

<gadget id="calculator">(1/3) - (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">20 / (1/12)</gadget>
<output>240</output>

<result>240</result>