One year later, the mother's age is four times that of Xiaoming's. The sum of the ages of Xiaoming and his mother this year is 38 years old. How old is Xiaoming this year?
1年后妈妈的年龄是小明年龄的4倍，今年小明和妈妈的年龄和是38岁，今年小明多少岁．
<gadget id="calculator">38 + 2</gadget>
<output>40</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

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

<result>7</result>