A barrel of oil is used up 60 grams per day on average. After 9 days of use, there are 460 grams left. How much does the barrel of oil weigh?
一桶油，平均每天用去60克，用了9天后，还剩460克，这桶油原来有多重？
<gadget id="calculator">60 * 9</gadget>
<output>540</output>

<gadget id="calculator">540 + 460</gadget>
<output>1_000</output>

<result>1_000</result>