In a ratio, the two internal terms are reciprocals of each other, one external term is (5/7), and the other external term is how much.
在一个比例里，两个内项互为倒数，一个外项是(5/7)，另一个外项是多少．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 / (5/7)</gadget>
<output>7/5 = around 1.4</output>

<result>7/5 = around 1.4</result>