In a ratio, the two outer terms are reciprocals, one of the inner terms is (1/7), and the other inner term is how much.
在一个比例里，两个外项为互倒数，其中一个内项是(1/7)，另一个内项是多少．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

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

<result>7</result>