A cuboid glass container with a length of 20 cm, a width of 10 cm, and a height of 30 cm contains some red solution. Xiao Ming wanted to know the depth of the solution. He inserted a cuboid wooden stick with a square bottom, side length 4 cm, and 1 meter long into the bottom of the container vertically. After taking it out, he measured that the part of the stick that was dyed red was 25 cm long. How many centimeters is the depth of the red solution in the original container?
一个长20厘米、宽10厘米、高30厘米的无盖长方体玻璃容器，里面盛有一些红色溶液．小明想知道溶液的深度，他将一根底面是正方形且边长4厘米，长1米的长方体木条垂直插入到容器底部，取出后量得木条被染红的部分长25厘米．原来容器内红色溶液深多少厘米．
<gadget id="calculator">20 * 10</gadget>
<output>200</output>

<gadget id="calculator">25 / 200</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">4 * 4 * (1/8)</gadget>
<output>2</output>

<gadget id="calculator">25 - 2</gadget>
<output>23</output>

<result>23</result>