passenger car travels from city A to city B for the whole journey (1/5) in the first hour, and 45 kilometers in the second hour. The ratio of the traveled distance to the remaining distance is 3:7. How many kilometers are there between the two cities?
一辆客车从甲城到乙城，第一小时行了全程的(1/5)，第二小时行了45千米，这时已行路程和剩下路程的比是3：7．甲乙两城相距多少千米？
<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">1 / 5</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">45 / (1/10)</gadget>
<output>450</output>

<result>450</result>