This year, the father is 36 years old. Three years ago, the age of the father was three times that of the son. How old is the son this year?
今年父亲36岁，三年前父亲的岁数是儿子的3倍，儿子今年多少岁．
<gadget id="calculator">36 - 3</gadget>
<output>33</output>

<gadget id="calculator">33 / 3</gadget>
<output>11</output>

<gadget id="calculator">11 + 3</gadget>
<output>14</output>

<result>14</result>