A car travels exactly 40% of the way in 2 hours. At this time, the car is still 252 kilometers away from the finish line. How many kilometers per hour does the car travel on average?
一辆汽车2小时正好走完全程的40%，这时汽车离终点还差252千米，这辆汽车平均每小时行驶多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">252 / (1/10)</gadget>
<output>2_520</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">2_520 * (1/5)</gadget>
<output>504</output>

<result>504</result>