Two trains, A and B, depart from cities A and B at the same time. They run towards each other and meet each other in 3 hours. The ratio of the distance traveled by the two trains when they meet is 3:4. It is known that train B travels 60 kilometers per hour. Find How many kilometers are there between A and B?
甲、乙两列火车同时从A、B两城开出，相向而行，3小时相遇，相遇时两车所行路程的比是3：4，已知乙车每小时行60千米，求A、B两城相距多少千米？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">3 / (4/7)</gadget>
<output>21/4 = around 5.25</output>

<gadget id="calculator">60 * (21/4)</gadget>
<output>315</output>

<result>315</result>