A passenger car travels from A to B on the first day (1/5) of the full length, and on the second day it travels 450 kilometers. At this time, the ratio of the distance traveled to the remaining distance is 3:7. How many kilometers are left without driving?
一辆客车从甲地到乙地，第一天行了全长的(1/5)，第二天行了450千米，这时已行驶的路程与剩下的路程比是3：7，还剩多少千米没有行驶？
<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">450 / (1/10)</gadget>
<output>4_500</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">4_500 * (7/10)</gadget>
<output>3_150</output>

<result>3_150</result>