In a ratio, the product of two outer terms is 1, one of the inner terms is 2.5, and what is the other inner term.
一个比例里，两个外项积是1，其中一个内项是2.5，另一个内项是多少．
<gadget id="calculator">1 / 2.5</gadget>
<output>0.4</output>

<result>0.4</result>