Put a potato and a tomato in a glass container with a bottom area of 3.6 decimeters (the potatoes and tomatoes are completely submerged in the water). The water level rises by 0.4 decimeters. After the tomatoes are taken out, the water level drops by 0.15 decimeters. The volume of the potatoes how many?
在一个底面积是3.6平方分米的玻璃容器中放入一个土豆和一个西红柿(土豆和西红柿完全浸没在水中)，水面上升0.4分米，取出西红柿后，水面又下降0.15分米，土豆的体积是多少？
<gadget id="calculator">0.4 - 0.15</gadget>
<output>0.25</output>

<gadget id="calculator">3.6 * 0.25</gadget>
<output>0.9</output>

<result>0.9</result>