This year, the combined age of the older brother and the younger brother is 50 years old. There was a year when the elder brother's age was the younger brother's age this year, and the older brother's age at that time was exactly twice the younger brother's age. How old is brother?
今年，哥哥、弟弟两人的岁数加起来是50岁，曾经有一年，哥哥的岁数是今年弟弟的岁数，那时哥哥的岁数恰好是弟弟岁数的2倍．哥哥今年多少岁．
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">50 / 5</gadget>
<output>10</output>

<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<result>30</result>