There is a fish tank without a cover, the length is 30cm, the width is 20cm, and the height is 40cm. Put a fish in this fish tank. The water surface rises from 18cm to 25cm. What is the volume of this fish?
有一种无盖的鱼缸，长30cm，宽20cm，高40cm，在这样的鱼缸中放入一条鱼，水面从18cm上升到25cm，这条鱼的体积是多少？
<gadget id="calculator">25 - 18</gadget>
<output>7</output>

<gadget id="calculator">30 * 20 * 7</gadget>
<output>4_200</output>

<result>4_200</result>