What is the result of (2/5)+(2/7)-(2/5)+(2/7)
(2/5)+(2/7)-(2/5)+(2/7)的结果是多少
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/7) - (2/5)</gadget>
<output>-4/35 = around -0.114286</output>

<gadget id="calculator">(2/5) + (-4/35) + (2/7)</gadget>
<output>4/7 = around 0.571429</output>

<result>4/7 = around 0.571429</result>