If 4X+1=9, then 2.5X-2=how much.
如果4X+1=9，那么2.5X-2=多少．
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

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

<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<result>3</result>