This year, the older sister is 20 years old, the older brother is 18 years old, the younger brother is 12 years old, and the younger sister is 8 years old. How many years later, the sum of the ages of the elder sister and elder brother is twice the age of the younger brother and younger sister.
今年姐姐20岁，哥哥18岁，弟弟12岁，妹妹8岁，多少年后，姐姐、哥哥年龄和的2倍等于弟弟、妹妹年龄和的3倍．
<gadget id="calculator">76 - 60</gadget>
<output>16</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<result>8</result>