There is a certain amount of water in a cylindrical container. The radius of the bottom surface of the cylinder is 20 cm, and the height is 50 cm (regardless of the thickness of the container). Now put a piece of cylindrical ice on the surface of the water. (No water overflows during ice placement and melting). It is known that the radius of the bottom of the cylindrical ice is 10 cm, and the height is 30 cm. After the ice melts, its volume will decrease by 10%. How high is the original water level in the container?
一个圆柱形的容器内装有水若干，圆柱的底面半径为20厘米，高为50厘米(不考虑容器的厚度)，现在往水面上放一块圆柱形状的冰，冰融化后容器内的水正好满了(冰在放置和融化过程中没有水溢出)．已知圆柱形冰的底面半径是10厘米，高为30厘米，冰融化后体积减少10%，问容器内原来的水面有多高？
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">3.14 * 400 * 50</gadget>
<output>62_800</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100 * 30</gadget>
<output>9_420</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">9_420 * (9/10)</gadget>
<output>8_478</output>

<gadget id="calculator">62_800 - 8_478</gadget>
<output>54_322</output>

<gadget id="calculator">3.14 * 400</gadget>
<output>1_256</output>

<gadget id="calculator">54_322 / 1_256</gadget>
<output>173/4 = around 43.25</output>

<result>173/4 = around 43.25</result>