The elder brother said to his younger brother: "5 years ago, I was 12 years older than you and three times your age", and asked my elder brother how old I am this year.
哥哥对弟弟说："5年前我的年龄比你大12岁，且是你的3倍"，问哥哥今年多少岁．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 + 5</gadget>
<output>23</output>

<result>23</result>