A passenger train and a freight train depart from two places at the same time. After meeting each other in 4 hours, the passenger train takes 7 hours to complete the journey, and the freight train travels 60 kilometers per hour. How many kilometers are the distance between the two places?
一列客车和一列货车同时从两地相对开出，经过4小时相遇，客车行完全程要用7小时，货车每小时行60千米，两地相距多少千米？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/4) - (1/7)</gadget>
<output>3/28 = around 0.107143</output>

<gadget id="calculator">60 / (3/28)</gadget>
<output>560</output>

<result>560</result>