A cube fish tank with a side length of 30cm is filled with water, and the water height is 20cm. After putting in the rockery stones, the water level rises to 25cm. What is the volume of the rockery rocks?
一个棱长为30cm的正方体鱼缸内盛水，水高20cm，现在放入假山石块后，水面上升到25cm，假山石块的体积是多少？
<gadget id="calculator">30 * 30 * 5</gadget>
<output>4_500</output>

<result>4_500</result>