A cuboid water tank is 15 decimeters high and the water depth inside is 6 decimeters. After a cylinder of iron is completely submerged in the water, the water surface height is 9.6 decimeters, and then a cone of iron is completely submerged in the water. It is known that the ratio of the radius of the cylinder iron block to the bottom surface of the cone iron block is 3:2, and the ratio of the height is 2:3. What is the current height of the water surface in decimeters?
一个长方体水箱，高15分米，里面水深6分米，把一个圆柱体铁块完全浸没在水中后，这时水面高度是9.6分米，接着又把一个圆锥体铁块完全浸没在水中．已知圆柱体铁块与圆锥体铁块底面半径的比是3：2，高的比是2：3，现在水面的高度是多少分米．
<gadget id="calculator">9.6 - 6</gadget>
<output>3.6</output>

<gadget id="calculator">3.6 / 9</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 * 2</gadget>
<output>0.8</output>

<gadget id="calculator">6 + 0.8</gadget>
<output>6.8</output>

<result>6.8</result>