The age ratio of A and B is 3:5, B is 8 years older than A, how old is A?
甲、乙两人的年龄比是3：5，乙比甲大8岁，甲是多少岁．
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<result>12</result>