cuboid glass tank filled with water is 10cm long, 4cm wide, and the height of the water surface is 8cm. There is also a small cube iron block with a side length of 2cm. If the iron block is taken out, how many cm will the water level drop?
一个有水的长方体玻璃缸，长10cm，宽4cm，水面的高度是8cm，里面还放着一个棱长2cm的小正方体铁块，如果把这个铁块取出来，水面会下降多少cm？
<gadget id="calculator">10 * 4</gadget>
<output>40</output>

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

<gadget id="calculator">2 * 2 * (1/20)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>