0.5(x-12)=3.
0.5(x-12)=3．
<gadget id="calculator">0.5 * 12</gadget>
<output>6</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">9 / 0.5</gadget>
<output>18</output>

<result>18</result>