My daughter is 12 years old this year (2013). The mother said to her daughter: "When you are my age, I will already be 60 years old!" So, how old is the mother when she is 12 years old?
女儿今年(2013年)12岁．妈妈对女儿说："当你有我这么大岁数时，我已经60岁喽！"那么，妈妈12岁时的年份是多少年．
<gadget id="calculator">60 - 12</gadget>
<output>48</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">48 / 2</gadget>
<output>24</output>

<gadget id="calculator">2_013 - 24</gadget>
<output>1_989</output>

<result>1_989</result>