The two outer terms of the ratio are 2 and X, and the two inner terms are (1/20) and 8, find X.
比的两个外项是2与X，两个内项是(1/20)与8，求X．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">8 * (1/20)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>