If the two inner terms of a ratio are 2 and 5, and one of the outer terms is 4, what is the other outer term?
一个比例的两个内项分别是2和5，其中一个外项是4，则另一个外项是多少．
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">2 * (5/4)</gadget>
<output>5/2 = around 2.5</output>

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