Xiao Ming is x years old this year, and his father is 42 years old this year. Three years later, his father is 27 years older than Xiao Ming. How old is Xiao Ming this year?
小明今年x岁，爸爸今年42岁，3年后爸爸比小明大27岁，小明今年多少岁？
<gadget id="calculator">42 - 27</gadget>
<output>15</output>

<result>15</result>