This year Xiaogang's father is 24 years older than Xiaogang. Three years later, Xiaogang's father will be three times as young as Xiaogang. How old is Xiaogang this year?
今年小刚的爸爸比小刚大24岁，3年后，小刚爸爸的年龄是小刚的3倍，小刚今年多少岁？
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

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

<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<result>9</result>