The two outer terms of the ratio are 2 and X, and the two inner terms are (1/20) and 8.
比的两个外项是2与X，两个内项是(1/20)与8．
<gadget id="calculator">2 * 8</gadget>
<output>16</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">16 / (1/20)</gadget>
<output>320</output>

<result>320</result>