If 7x is 2.4 smaller than 9x, then x=how much.
如果7x比9x小2.4，那么x=多少．
<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<gadget id="calculator">2.4 / 2</gadget>
<output>1.2</output>

<result>1.2</result>