In a ratio, the two internal terms are reciprocals of each other, one of the external terms is 7, and the other external term is how much.
在一个比例里，两个内项互为倒数，其中一个外项是7，另一个外项是多少．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>