cuboid water tank has a length of 40 cm and a width of 35 cm measured from the inside, and there is a certain amount of water in the tank. A steel ball is completely submerged in water. At this time, the liquid level is 15cm. After taking out the steel ball, the liquid level is 12cm. It is known that the mass of steel per cubic decimeter is 7.8kg, how many kilograms does this steel ball weigh? (water not overflowing)
一个长方体水箱，从里面量长为40cm、宽为35cm，水箱内有一定量的水．将一个钢球完全浸没在水中，这时液面高为15cm，取出钢球后，液面高为12cm．已知每立方分米钢的质量是7.8kg，这个钢球重多少千克？(水未溢出)
<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<gadget id="calculator">3 / 1_000</gadget>
<output>3/1_000 = around 0.003</output>

<gadget id="calculator">40 * 35 * (3/1_000) * 7.8</gadget>
<output>32.76</output>

<result>32.76</result>