Calculation: (6/13)-(3/7)+(7/13)-(2/7).
计算：(6/13)-(3/7)+(7/13)-(2/7)．
<gadget id="calculator">6 / 13</gadget>
<output>6/13 = around 0.461538</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(6/13) - (3/7)</gadget>
<output>3/91 = around 0.032967</output>

<gadget id="calculator">7 / 13</gadget>
<output>7/13 = around 0.538462</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(7/13) - (2/7)</gadget>
<output>23/91 = around 0.252747</output>

<gadget id="calculator">(3/91) + (23/91)</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>