The combination of (9/20) and a number is (11/20), what is this number?
(9/20)与一个数合起来是(11/20)，这个数是多少？
<gadget id="calculator">11 / 20</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(11/20) - (9/20)</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>