If x and y are inversely proportional, when x=4, y=9, when x=6, y=how much.
若x与y成反比例关系，当x=4时y=9，当x=6时，y=多少．
<gadget id="calculator">4 * 9</gadget>
<output>36</output>

<gadget id="calculator">36 / 6</gadget>
<output>6</output>

<result>6</result>