A passenger car travels 20% of the whole journey from A to B on the first day, and 450km on the second day. At this time, the ratio of the traveled distance to the remaining distance is 3:7. How much is the distance between A and B?
一辆客车从甲地到乙地，第一天行了全程的20%，第二天行了450km，这时已行路程和剩下路程的比是3：7．甲乙两地相距多少？
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/10) - (1/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">450 / (1/10)</gadget>
<output>4_500</output>

<result>4_500</result>