If X/2.5=3, then 2X+1=how much.
如果X/2.5=3，那么2X+1=多少．
<gadget id="calculator">1 / 2.5</gadget>
<output>0.4</output>

<gadget id="calculator">3 / 0.4</gadget>
<output>7.5</output>

<gadget id="calculator">2 * 7.5</gadget>
<output>15</output>

<gadget id="calculator">15 + 1</gadget>
<output>16</output>

<result>16</result>