In a ratio, the two outer terms are reciprocals of each other, one inner term is 20, and the other inner term is 20.
在一个比例中，两外项互为倒数，一个内项20，另个内项是多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<result>1/20 = around 0.05</result>