Dad is 30 years old this year, and his son is 3 years old this year. Eight years later, how much older will the father be than the son?
爸爸今年30岁，他的儿子今年3岁，8年后，爸爸比儿子大多少岁．
<gadget id="calculator">30 - 3</gadget>
<output>27</output>

<result>27</result>