There is a rectangular container with a bottom side of 40 cm in length. A cuboid iron block with a bottom side of 10 cm in length and a height of 90 cm is vertically placed in the container. The depth of water in the container is 80 cm. When the cuboid iron block is lifted up slightly by 30 cm, how long is the part of the iron block exposed to the water that is wetted by water in cm?
有一长方形容器，底面边长为40cm，容器中竖直放着一个底面边长为10cm、高位90cm的长方体铁块，这时容器中水深为80cm．将长方体铁块轻轻向上提起30cm时，露出水面的铁块被水浸湿的部分长多少cm？
<gadget id="calculator">10 * 10 * 30</gadget>
<output>3_000</output>

<gadget id="calculator">40 * 40</gadget>
<output>1_600</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<gadget id="calculator">1_600 - 100</gadget>
<output>1_500</output>

<gadget id="calculator">3_000 / 1_500</gadget>
<output>2</output>

<gadget id="calculator">30 + 2</gadget>
<output>32</output>

<result>32</result>