((0.3)/(0.5))=((x+1)/(2x-1)).
((0.3)/(0.5))=((x+1)/(2x-1))．
<gadget id="calculator">0.3 + 0.5</gadget>
<output>0.8</output>

<gadget id="calculator">0.3 * 2</gadget>
<output>0.6</output>

<gadget id="calculator">0.6 - 0.5</gadget>
<output>0.1</output>

<gadget id="calculator">0.8 / 0.1</gadget>
<output>8</output>

<result>8</result>