The wholesale price of mineral water is 3 yuan per barrel, and the retail price is 5 yuan per barrel. Master Wang earned 66 yuan. How many barrels of water did he sell?
矿泉水批发价是每桶3元，零售价是每桶5元，王师傅赚了66元，他卖出了多少桶水？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">66 / 2</gadget>
<output>33</output>

<result>33</result>