Take the third question (that is, when grandma is 21 years old, father is 1 year old; when father is 39 years old, Xiaoyun is 8 years old.), what is the age difference between Xiaoyun and grandma after 25 years.
接第3题(即奶奶21岁时，爸爸1岁；爸爸39岁时，小芸8岁．)，25年后小芸和奶奶相差多少岁．
<gadget id="calculator">39 - 1</gadget>
<output>38</output>

<gadget id="calculator">21 + 38</gadget>
<output>59</output>

<gadget id="calculator">59 - 8</gadget>
<output>51</output>

<result>51</result>