If 4 is the middle term in the ratio of x and 8, then x = how much.
如果4是x和8的比例中项，那么x=多少．
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">16 / 8</gadget>
<output>2</output>

<result>2</result>