Cars A and B start from AB at the same time, and after 3 hours of traveling towards each other, car A meets car B at (3/7) of the whole journey. It is known that car A travels 30 kilometers per hour, and car B travels the entire distance It takes 5 (1/4) hours, how many kilometers is the distance between AB and AB?
甲乙两车从AB两地同时出发，相向而行3小时后，甲车行到全程的(3/7)处与乙车相遇，已知甲车每小时行30千米，乙车行完全程要5(1/4)小时，求AB两地相距多少千米？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">3 / (3/7)</gadget>
<output>7</output>

<gadget id="calculator">30 * 7</gadget>
<output>210</output>

<result>210</result>