Xiao Ming is 6 years old this year, and his mother is 30 years old this year. After many years, his mother's age will be three times that of Xiao Ming.
小明今年6岁，妈妈今年30岁，再过多少年，妈妈的年龄是小明的3倍．
<gadget id="calculator">30 - 6</gadget>
<output>24</output>

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

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

<gadget id="calculator">12 - 6</gadget>
<output>6</output>

<result>6</result>