Every 3 empty bottles can be exchanged for a bottle of soda. Someone bought 27 bottles of soda, and then exchanged the empty bottle for soda after drinking. So, how many bottles of soda should he drink? (writing process)
每3个空瓶可以换一瓶汽水，有人买了27瓶汽水，喝完后又用空瓶换汽水，那么，他最式喝多少瓶汽水？(写出过程)
<gadget id="calculator">27 / 3</gadget>
<output>9</output>

<gadget id="calculator">27 / 3 / 3</gadget>
<output>3</output>

<gadget id="calculator">27 + 9 + 3 + 1</gadget>
<output>40</output>

<result>40</result>