In the ratio, the two outer terms are the reciprocals of each other, one of the inner terms is 4.5, and the other inner term is 4.5.
在比例中，两个外项互为倒数，其中一个内项是4.5，另一个内项是多少．
<gadget id="calculator">1 / 4.5</gadget>
<output>0.222222</output>

<result>0.222222</result>