There is 84.78 liters of oil in a cylindrical oil barrel, which is equivalent to 80% of the volume of the oil barrel. The radius of the bottom surface is 3 decimeters. How many decimeters is the distance between the oil surface and the upper bottom of the oil barrel?
一个圆柱形油桶内有油84.78升，相当于油桶容积的80%，底面半径是3分米，油面距油桶上底面多少分米？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">84.78 / (4/5)</gadget>
<output>105.975</output>

<gadget id="calculator">105.975 - 84.78</gadget>
<output>21.195</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<gadget id="calculator">21.195 / 28.26</gadget>
<output>0.75</output>

<result>0.75</result>