Two fast and slow cars leave opposite directions at the same time from A and B, and meet at a distance of 30 kilometers from the midpoint. How many kilometers has the fast car traveled more than the slow car?
快慢两车同时从甲、乙两地相向开出，在距离中点30千米处相遇，快车比慢车多行了多少千米．
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>