A cylindrical oil barrel with a diameter of 30 cm at the bottom and a height of 40 cm is filled with gasoline. If all the gasoline in the barrel is poured into a cuboid fuel tank, the fuel tank is still empty (1/4). The bottom area of this fuel tank is 471 square centimeters. How tall is the fuel tank in cm?
一个圆柱形的油桶，桶内底面直径是30厘米，高40厘米，桶里盛满汽油．如果把桶里汽油全部倒进一个长方体油箱，油箱还空着(1/4)．这个油箱的底面积是471平方厘米．这个油箱的高有多少厘米？
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">15 ** 2</gadget>
<output>225</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">40 / (3/4) / 471</gadget>
<output>160/1_413 = around 0.113234</output>

<gadget id="calculator">3.14 * 225 * (160/1_413)</gadget>
<output>80</output>

<result>80</result>