A cuboid glass fish tank measures 80 cm in length, 50 cm in width and 20 cm in water depth. Now put 40 goldfish in the tank. The ratio of the rising distance of the water surface to the original water depth is 1:10. The average volume of each goldfish is How many?
一个长方体的玻璃鱼缸，从里面量长80厘米，宽50厘米，水深20厘米，现在把40条金鱼放入鱼缸内，水面上升的距离与原来水深比1：10，平均每条金鱼的体积是多少？
<gadget id="calculator">20 / 10</gadget>
<output>2</output>

<gadget id="calculator">2 / 40</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">80 * 50 * (1/20)</gadget>
<output>200</output>

<result>200</result>