car drives from place A to place B. It travels 25% of the journey in the first hour, and 50 kilometers in the second hour. In two hours, it travels a total of 45% of the journey. How many kilometers are there between A and B?
一辆汽车从甲地开往乙地，第1小时行了全程的25%，第2小时行了50千米，两个小时一共行了全程的45%．甲、乙两地相距多少千米？
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(9/20) - (1/4)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">50 / (1/5)</gadget>
<output>250</output>

<result>250</result>