Cars A and B set off from cities A and B at the same time, and drive toward each other. They meet at 4 o'clock, and the meeting point is 10 kilometers away from the midpoint. It is known that the speed ratio of car A and car B is 7:6. Find the distance between cities A and B.
甲、乙两车分别从A、B两城同时出发，相向而行，经过4时相遇，相遇点距中点10千米．已知甲车与乙车的速度比为7：6．求A、B两城的距离．
<gadget id="calculator">7 + 6</gadget>
<output>13</output>

<gadget id="calculator">7 / 13</gadget>
<output>7/13 = around 0.538462</output>

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

<gadget id="calculator">(7/13) - (1/2)</gadget>
<output>1/26 = around 0.038462</output>

<gadget id="calculator">10 / (1/26)</gadget>
<output>260</output>

<result>260</result>