A kind of salt water, salt accounts for (1/10) of salt water, how much salt accounts for water
一种盐水，盐占盐水的(1/10)，盐占水的多少
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(1/10) / (9/10)</gadget>
<output>1/9 = around 0.111111</output>

<result>1/9 = around 0.111111</result>