The sum of the ages of the two brothers this year is 50 years old. When the elder brother is as old as the younger brother now, and the younger brother’s age is exactly the elder brother’s current age (4/7), what is the elder brother’s age this year?
兄弟俩今年的年龄和是50岁，当哥哥像弟弟现在这样大时，弟弟的年龄恰好是哥哥今年年龄的(4/7)，则哥哥今年的年龄是多少岁．
<gadget id="calculator">50 + 50</gadget>
<output>100</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 + 2 + (4/7)</gadget>
<output>25/7 = around 3.571429</output>

<gadget id="calculator">100 / (25/7)</gadget>
<output>28</output>

<result>28</result>