A waterless ornamental fish tank is 50 cm long and 35 cm wide, and there is a fake rock mountain with a height of 30 cm and a volume of 300 cm**3 inside. If the water pipe injects water into the fish tank at a flow rate of 9dm**3 per minute, how long will it take at least to completely submerge the rocky mountain?
一个无水观赏鱼缸长50厘米，宽35厘米，里面放有一块高为30cm，体积为300cm**3的假石山．如果水管以每分钟9dm**3的流量向鱼缸内注水，至少需要多少时间才能将假石山完全淹没？
<gadget id="calculator">50 * 35 * 30</gadget>
<output>52_500</output>

<gadget id="calculator">52_500 - 300</gadget>
<output>52_200</output>

<gadget id="calculator">9 * 1_000</gadget>
<output>9_000</output>

<gadget id="calculator">52_200 / 9_000</gadget>
<output>29/5 = around 5.8</output>

<result>29/5 = around 5.8</result>