A cylindrical bucket with a height of 8 decimeters is half filled with water. After pouring out 12 liters of water, the remaining water occupies exactly (2/5) the volume of the bucket. What is the area of the bottom of this bucket in square decimeters?
一个高为8分米的圆柱形水桶里，装了半桶水．把水倒出12升后，剩下的水恰好占水桶容积的(2/5)．这个水桶的底面积是多少平方分米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">12 / (1/10) / 8</gadget>
<output>15</output>

<result>15</result>