Zhang Liang travels from City A to City B. On the first day, he travels 40% of the whole journey, and on the second day (9/20), he is still 900 meters away from City B. How many meters are there between the two cities?
张亮从甲城到乙城，第一天行了全程的40%，第二天行了全程的(9/20)，距乙城还有900米，甲乙两城相距多少米？
<gadget id="calculator">40 / 100</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)</gadget>
<output>6_000</output>

<result>6_000</result>