There are three cube pools A, B, and C. Their inner edge lengths are 40dm, 30dm, and 20dm respectively. Put some gravel in the two pools of B and C (the gravel is completely immersed in the water), and the two pools The water level rises by 6cm and 6.5cm respectively. If these gravels are put into pool A (the gravels are completely submerged in water), how many decimeters will the water level of pool A be raised? (The water in the three pools is not overflowing)
有甲、乙、丙三个正方体水池，它们的内棱长分别为40dm，30dm，20dm，在乙、丙两个水池中分别放入一些碎石(碎石完全浸入水中)，两个水池的水面分别升高了6cm和6.5cm．如果把这些碎石放入甲水池(碎石完全浸入水中)，甲水池的水面将升高多少分米？(三个水池中的水都未溢出)
<gadget id="calculator">30 * 30 * 0.6</gadget>
<output>540</output>

<gadget id="calculator">20 * 20 * 0.65</gadget>
<output>260</output>

<gadget id="calculator">540 + 260</gadget>
<output>800</output>

<gadget id="calculator">40 * 40</gadget>
<output>1_600</output>

<gadget id="calculator">800 / 1_600</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>