A passenger car and a truck drive towards each other from A and B at the same time. It is known that the speed ratio of the truck and the passenger car is 5:7. After 5 hours, the two cars meet at a distance of 120 kilometers from the midpoint. Find the distance in kilometers between A and B.
客车和货车同时从甲乙两地相向而行，已知货车与客车的速度比是5：7，5小时后两车在距中点120千米处相遇，求甲乙两地相距多少千米．
<gadget id="calculator">5 + 7</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>