In a ratio, the two outer terms are reciprocals of each other. It is known that one of the inner terms is (2/5) and the other inner term is.
在一个比例里，两个外项互为倒数，已知其中一个内项是(2/5)，另一个内项是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / (2/5)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>