In 2012, the age of the father was four times the sum of the ages of the elder sister and younger brother; if another 6 years passed, the age of the father was twice the age of the elder sister and younger brother. So, when was the father born?
2012年时，父亲的年龄是姐姐和弟弟年龄之和的4倍；若再过6年，父亲的年龄就是姐姐和弟弟年龄之和的2倍．那么，父亲出生在多少年．
<gadget id="calculator">12 - 3</gadget>
<output>9</output>

<gadget id="calculator">4 * 9</gadget>
<output>36</output>

<gadget id="calculator">2_012 - 36</gadget>
<output>1_976</output>

<result>1_976</result>