There is a 30-year age difference between Xiaohua and her mother. In three years, her mother’s age will be 3.5 times Xiaohua’s age. Do you know how old Xiaohua is this year? (solution by equation)
小华和妈妈现在相差30岁，再过3年，妈妈的年龄就是小华年龄的3.5倍，你知道小华今年几岁吗？(用方程解)
<gadget id="calculator">3.5 - 1</gadget>
<output>2.5</output>

<gadget id="calculator">30 / 2.5</gadget>
<output>12</output>

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

<result>9</result>