If 3x+4=25, then 4x-6=how much.
若3x+4=25，那么4x-6=多少．
<gadget id="calculator">25 - 4</gadget>
<output>21</output>

<gadget id="calculator">21 / 3</gadget>
<output>7</output>

<gadget id="calculator">4 * 7</gadget>
<output>28</output>

<gadget id="calculator">28 - 6</gadget>
<output>22</output>

<result>22</result>