((x-2)/(0.2))-((x+1)/(0.5))=3.
((x-2)/(0.2))-((x+1)/(0.5))=3．
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 2 + 3</gadget>
<output>15</output>

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

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<result>5</result>