4x-2x=3*18．
4x-2x=3*18．
<gadget id="calculator">3 * 18</gadget>
<output>54</output>

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

<gadget id="calculator">54 / 2</gadget>
<output>27</output>

<result>27</result>