cylindrical tin barrel is filled with gasoline. After pouring out (3/4) of the gasoline in the barrel, there are 18 liters left. It is known that the height of the oil barrel measured from the inside is 12 decimeters, what is the area of its bottom in square decimeters?
一个圆柱形铁皮桶内装满了汽油，把桶内的汽油倒出(3/4)后，还剩18升．已知从内侧量，油桶的高是12分米，它的底面积是多少平方分米？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">18 / (1/4)</gadget>
<output>72</output>

<gadget id="calculator">72 / 12</gadget>
<output>6</output>

<result>6</result>