A cuboid fish tank is 15 cm long and 10 cm wide, filled with water 5 cm high. After putting two goldfishes in, the height of the water surface is 5.02 cm. Find the space occupied by the two goldfishes.
一个长方体鱼缸，长15厘米，宽10厘米，里面装了高5厘米的水．放进两条金鱼后，水面高度是5.02厘米，求两条金鱼所占的空间．
<gadget id="calculator">5.02 - 5</gadget>
<output>0.02</output>

<gadget id="calculator">15 * 10 * 0.02</gadget>
<output>3</output>

<result>3</result>