If 6 is the middle term in the ratio of x to 4, then x = how much.
如果6是x和4的比例中项，那么x=多少．
<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<result>9</result>