What is the reciprocal of the sum of (3/4) and (4/7).
(3/4)与(4/7)的和的倒数是多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) + (4/7)</gadget>
<output>37/28 = around 1.321429</output>

<gadget id="calculator">1 / (37/28)</gadget>
<output>28/37 = around 0.756757</output>

<result>28/37 = around 0.756757</result>