Xiao Ning is 7 years old this year, and the combined age of her parents is 71 years old. After many years, the average age of their family of three is 34 years old.
小宁今年7岁，爸爸妈妈两人的年龄和是71岁，多少年后，他们一家三口的平均年龄是34岁．
<gadget id="calculator">34 * 3</gadget>
<output>102</output>

<gadget id="calculator">7 + 71</gadget>
<output>78</output>

<gadget id="calculator">102 - 78</gadget>
<output>24</output>

<gadget id="calculator">24 / 3</gadget>
<output>8</output>

<result>8</result>