A cuboid water tank with a length of 5 decimeters, a width of 4 decimeters and a height of 4 decimeters has a water depth of 30 centimeters. After a coconut is completely submerged in the water, the water level rises by 4 centimeters. What is the volume of the coconut in cubic decimeters?
一个长5分米、宽和高都是4分米的长方体水箱里有水深30厘米，把一个椰子放进水里完全沉没后，水面上升了4厘米，这个椰子的体积是多少立方分米．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 * 4 * (2/5)</gadget>
<output>8</output>

<result>8</result>