If 2x+1=9, then 5x+0.5=how much.
如果2x+1=9，那么5x+0.5=多少．
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 + 0.5</gadget>
<output>20.5</output>

<result>20.5</result>