A cuboid container is 50cm long and 40cm wide. A cuboid iron block with a height of 1m and a side length of 20cm is erected in the container. At this time, the water depth in the container is 40cm. Now lift the iron block slightly upwards by 20cm, how many centimeters is the wetted part of the iron block exposed to the water?
一个长方体容器，长50cm，宽40cm，容器里直立一根高1m，底面边长为20cm的长方体铁块，这时容器里的水深40cm．现在把铁块轻轻向上提起20cm，那么露出水面的铁块上被浸湿的部分长多少厘米？
<gadget id="calculator">50 * 40</gadget>
<output>2_000</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">2_000 - 400</gadget>
<output>1_600</output>

<gadget id="calculator">20 / 1_600</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">20 * 20 * (1/80)</gadget>
<output>5</output>

<gadget id="calculator">5 + 20</gadget>
<output>25</output>

<result>25</result>