Dad is 40 years old this year. His age 15 years ago is the same as Xiao Wei's age 13 years later. How old is Xiao Wei this year?
爸爸今年40岁，他15年前的年龄与小薇13年后的年龄相等，小薇今年几岁？
<gadget id="calculator">40 - 13 - 15</gadget>
<output>12</output>

<result>12</result>