cylindrical oil barrel is filled with gasoline. After the gasoline in the barrel is pumped out (2/5), there are 18 liters of gasoline left in the barrel. The bottom area of the oil barrel is 5 square decimeters, how many decimeters is the height of the oil barrel?
一个圆柱形油桶里装满了汽油，把桶里的汽油抽出(2/5)后，桶内还剩18升汽油．油桶的底面积是5平方分米，油桶的高是多少分米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">18 / (3/5) / 5</gadget>
<output>6</output>

<result>6</result>