A passenger car and a truck leave opposite directions at a small station on the way between A and B at the same time. After 4:00, the bus arrives at A and the truck arrives at B. Passenger cars travel an average of 65 kilometers per hour, and trucks travel an average of 35 kilometers per hour. Find the distance between A and B in kilometers?
一客车和一货车同时从A、B两地途中的一小车站相背开出，4时后，客车到达A地，货车到达B地．客车平均每小时行65千米，货车平均每小时行35千米．求A、B两地相距多少千米？
<gadget id="calculator">65 + 35</gadget>
<output>100</output>

<gadget id="calculator">100 * 4</gadget>
<output>400</output>

<result>400</result>