A passenger car departs from A to B, and a train departs from B to A. The two trains leave at the same time, and they can meet each other in 9 hours. Then they continued to drive for another 3 hours. At this time, the bus was 420 kilometers away from place B, and the truck was 3 kilometers away from place A. How many kilometers are there between A and B?
客车从甲地开往乙地，火车从乙地开往甲地，两车同时开出，9小时可以相遇．然后各自又继续行驶了3小时，这时客车离乙地420千米，货车离甲地3千米．甲、乙两地相距多少千米？
<gadget id="calculator">420 + 3</gadget>
<output>423</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<gadget id="calculator">423 / 6</gadget>
<output>141/2 = around 70.5</output>

<gadget id="calculator">(141/2) * 9</gadget>
<output>1_269/2 = around 634.5</output>

<result>1_269/2 = around 634.5</result>