The sum of the ages of A and B is a prime number. The sum of the ones and tens digits of this two-digit number is 13. A is 13 years older than B. So how old is B this year?
甲乙两人的年龄和为一个质数，这个两位数的个位与十位数字的和是13，甲比乙大13岁，那么乙今年多大？
<gadget id="calculator">67 - 13</gadget>
<output>54</output>

<gadget id="calculator">54 / 2</gadget>
<output>27</output>

<result>27</result>