The father is 39 years old, 3 years older than the son's age. How old is the son?
爸爸今年39岁，比儿子年龄的3倍多3岁，儿子今年几岁？
<gadget id="calculator">39 - 3</gadget>
<output>36</output>

<gadget id="calculator">36 / 3</gadget>
<output>12</output>

<result>12</result>