(1-(3.1-3.09))/(0.8+(13/15)).
(1-(3.1-3.09))/(0.8+(13/15))．
<gadget id="calculator">3.1 - 3.09</gadget>
<output>0.01</output>

<gadget id="calculator">1 - 0.01</gadget>
<output>0.99</output>

<gadget id="calculator">13 / 15</gadget>
<output>13/15 = around 0.866667</output>

<gadget id="calculator">0.8 + (13/15)</gadget>
<output>1.666667</output>

<gadget id="calculator">0.99 / 1.666667</gadget>
<output>0.594</output>

<result>0.594</result>