Now the younger brother's age is exactly (1/2) of the older brother's age, but nine years ago the younger brother's age was only (1/5) of the older brother's age. How old is the older brother this year?
现在弟弟的年龄恰好是哥哥年龄的(1/2)，而九年前弟弟年龄只是哥哥的(1/5)，今年哥哥有多少岁．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">9 * (1/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">9 - (9/5)</gadget>
<output>36/5 = around 7.2</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(36/5) / (3/10)</gadget>
<output>24</output>

<result>24</result>