An express train and a slow train leave opposite directions at the same time from places A and B, and meet at a distance of 120 kilometers from the midpoint after 3 hours. It is known that the speed of the slow train is the speed of the express train (5/7), find A and B How many kilometers are the distance between the two places?
一辆快车和一辆慢车同时从甲、乙两地相向开出，3小时后在距离中点120千米处相遇，已知慢车速度是快车的速度的(5/7)，求甲、乙两地相距多少千米？
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(7/12) - (1/2)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">120 / (1/12)</gadget>
<output>1_440</output>

<result>1_440</result>