cylindrical glass tank, the diameter of the bottom surface measured from the inside is 20 cm, and the depth is 15 cm. Fill the tank with water and pour it into an empty cuboid goldfish tank. It is known that the length, width, and height of the tank are measured from the inside. The heights are 40 cm, 20 cm, and 30 cm, respectively. What is the height of the water surface in the fish tank?
一个圆柱形玻璃水槽，从里面量得底面的直径是20厘米，深15厘米，用这个水槽装满水，在倒入一个空长方体金鱼缸中，已知从里面量得鱼缸的长、宽、高分别是40厘米、20厘米、30厘米．求鱼缸中水面的高度是多少厘米？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

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

<gadget id="calculator">40 * 20</gadget>
<output>800</output>

<gadget id="calculator">15 / 800</gadget>
<output>3/160 = around 0.01875</output>

<gadget id="calculator">3.14 * 100 * (3/160)</gadget>
<output>5.8875</output>

<result>5.8875</result>