Xiao Ming's age this year is a quarter of his father's. Three years ago, the sum of father and son's age was 49. How old is Xiao Ming this year?
今年小明的年龄是爸爸的四分之一，三年前父子年龄的和是49岁，小明今年多少岁？
<gadget id="calculator">3 + 3 + 49</gadget>
<output>55</output>

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

<gadget id="calculator">55 / 5</gadget>
<output>11</output>

<result>11</result>