It costs 300 yuan to buy 5 barrels of oil, and each barrel of oil weighs 4 kilograms. How much is the average per kilogram?
买5桶油一共要300元，每桶油重4千克．平均每千克多少元？
<gadget id="calculator">300 / 5 / 4</gadget>
<output>15</output>

<result>15</result>