A cuboid reservoir is 4 meters deep. If 40 cubic meters of water are injected per minute, it can be filled in 40 minutes. What is the bottom area of the reservoir?
一个长方体的蓄水池深4米，如果每分钟注水40立方米，40分钟可以注满，这个水池的底面积是多少？
<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<gadget id="calculator">40 * 10</gadget>
<output>400</output>

<result>400</result>