The sum of the ages of the father and his three sons is 108 years. If another 6 years pass, the age of the father is exactly equal to the sum of the ages of the three sons. How old is the father now?
父亲与三个儿子年龄和是108岁，若再过6年，父亲的年龄正好等于三个儿子年龄的和．父亲现年多少岁．
<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<gadget id="calculator">24 + 108</gadget>
<output>132</output>

<gadget id="calculator">132 / 2</gadget>
<output>66</output>

<gadget id="calculator">66 - 6</gadget>
<output>60</output>

<result>60</result>