A cylindrical oil barrel contains 30 liters of oil, which is 3/5 of the volume of the entire oil barrel. It is known that the height of the oil barrel is 1.2 meters. Find the bottom area of the oil barrel.
一个圆柱形油桶，里面的油剩下30升，是整个油桶容积的(3/5)，已知这个油桶的高是1.2米，求这个油桶的底面积．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1.2 * 10</gadget>
<output>12</output>

<gadget id="calculator">30 / (3/5) / 12</gadget>
<output>25/6 = around 4.166667</output>

<result>25/6 = around 4.166667</result>