Nini is 9 years old this year, and her father is 35 years old. When Nini was old, her father was exactly three times Nini's age.
妮妮今年9岁，爸爸今年35岁，妮妮多少岁时，爸爸的年龄正好是妮妮的3倍．
<gadget id="calculator">35 - 9</gadget>
<output>26</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<result>13</result>