(7/12)-(9/20)+(11/30)-(13/42)+(15/56)-(17/72).
(7/12)-(9/20)+(11/30)-(13/42)+(15/56)-(17/72)．
<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

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

<gadget id="calculator">(7/12) - (9/20)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">11 / 30</gadget>
<output>11/30 = around 0.366667</output>

<gadget id="calculator">13 / 42</gadget>
<output>13/42 = around 0.309524</output>

<gadget id="calculator">(11/30) - (13/42)</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">15 / 56</gadget>
<output>15/56 = around 0.267857</output>

<gadget id="calculator">17 / 72</gadget>
<output>17/72 = around 0.236111</output>

<gadget id="calculator">(15/56) - (17/72)</gadget>
<output>2/63 = around 0.031746</output>

<gadget id="calculator">(2/15) + (2/35) + (2/63)</gadget>
<output>2/9 = around 0.222222</output>

<result>2/9 = around 0.222222</result>