A cuboid tank filled with water has a bottom surface of a square with a side length of 6 decimeters, and a cuboid iron block with a length of 5 decimeters and a width of 4 decimeters is immersed in it. When the iron block was taken out, the water level in the tank dropped by 2 decimeters. How many decimeters is the height of the cuboid iron block?
一个盛着水的长方体水缸，它的底面是边长6分米的正方形，里面浸没着一个长5分米，宽4分米的长方体铁块．当把这个铁块取出来后，水缸里的水面下降了2分米．求长方体铁块的高是多少分米？
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">6 * 6 * (1/10)</gadget>
<output>18/5 = around 3.6</output>

<result>18/5 = around 3.6</result>