Uncle Wang's age 15 years ago is equal to Xiao Ming's age 6 years later. Seven years ago, Uncle Wang was eight times as old as Xiao Ming. How old is Xiao Ming this year?
王叔叔15年前的年龄等于小明6年后的年龄．7年前，王叔叔的年龄是小明的8倍，小明今年多少岁？
<gadget id="calculator">15 + 6</gadget>
<output>21</output>

<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">21 / 7</gadget>
<output>3</output>

<gadget id="calculator">7 + 3</gadget>
<output>10</output>

<result>10</result>