The length of a fish tank is 40cm, the width is 2dm, and the height is 15cm. After filling the water, the water depth is 8cm. After the mother bought 5 fish and put them into the fish tank, the water depth is 12cm. What is the average volume of each fish in cubic centimeters? ?
一个鱼缸从里面量长是40cm、宽是2dm、高是15cm，注入水后，水深8cm，妈妈买回来5条鱼放入鱼缸后的水深是12cm，平均每条鱼的体积大约是多少立方厘米？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 * 20 * (4/5)</gadget>
<output>640</output>

<result>640</result>