Xiaogang went from place A to place B. He traveled 2/5 of the whole journey in the first hour, and 9/20 of the whole journey in the second hour. He is still 900 meters away from place B. How many kilometers is the distance from place A to place B? ?
小刚从甲地到乙地，第一小时行了全程的2/5，第二小时行了全程的(9/20)，距乙地还有900米，甲地到乙地相距多少千米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (2/5) - (9/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">900 / (3/20) / 1_000</gadget>
<output>6</output>

<result>6</result>