cuboid water tank, the bottom surface is a square with a side length of 2 decimeters, the height is 30 cm, and the height of the water surface is 15 cm. Put a cuboid with a length of 10 cm, a width of 8 cm and a height of 5 cm. What is the height of the water surface in cm?
一个长方体水箱，底面是一个边长2分米的正方形，高是30厘米，水面高度是15厘米，放入长10厘米、宽8厘米高5厘米的长方体，此时水面的高度是多少厘米？
<gadget id="calculator">2 * 10</gadget>
<output>20</output>

<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">15 / 80</gadget>
<output>3/16 = around 0.1875</output>

<gadget id="calculator">20 * 20 * (3/16)</gadget>
<output>75</output>

<result>75</result>