4 years ago, the age of the father was three times that of the son. This year, the father is 24 years older than the son. How old is the son this year?
4年前，父亲的年龄是儿子的3倍，今年父亲比儿子大24岁，今年儿子多少岁
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">12 + 4</gadget>
<output>16</output>

<result>16</result>