The speeds of cars, vans and buses are 90 km/h, 72 km/h and 63 km/h respectively. A car and a bus depart from A, and a van departs from B at the same time. The van encounters the car 30 minutes later and encounters the bus. How many kilometers is the distance between A and B?
小轿车、面包车和大客车的速度分别是90千米/小时、72千米/小时和63千米/小时．小轿车和大客车从甲地，面包车从乙地同时相向出发，面包车遇到小轿车后30分钟又遇到大客车，问甲、乙两地相距多少千米？
<gadget id="calculator">0 + 0.5</gadget>
<output>0.5</output>

<gadget id="calculator">810 * 0.5</gadget>
<output>405</output>

<result>405</result>