From A to B, (2/7) is the uphill road, (4/7) is the flat road, and the rest are downhill. Xiaoduo goes back and forth between A and B and goes downhill (3/8 ) kilometers, how many kilometers did Xiaoduo walk uphill from point B back to point A?
从甲地到乙地，其中(2/7)是上破路，(4/7)是平坦路，其余是下坡路，小朵在甲、乙两地间往返一趟共走下坡路(3/8)千米，小朵从乙地回甲地走了多少千米上坡路？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

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

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (2/7) - (4/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(2/7) + (1/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/8) / (3/7)</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">(7/8) * (1/7)</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>