The number of A's age is reversed, and it happens to be B's age. The sum of the ages of the two is 99 years old, and A is 9 years older than B. What is A's age?
甲的年龄数颠倒过来，恰好是乙的年龄，两人的年龄和是99岁，甲比乙大9岁．甲的年龄是多少岁．
<gadget id="calculator">99 + 9</gadget>
<output>108</output>

<gadget id="calculator">108 / 2</gadget>
<output>54</output>

<result>54</result>