It is known that the product of three numbers is (3/7), two of which are reciprocals of each other, what is the reciprocal of the third number.
已知三个数的积是(3/7)，其中有两个数互为倒数，第三个数的倒数是多少．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 / (3/7)</gadget>
<output>7/3 = around 2.333333</output>

<result>7/3 = around 2.333333</result>