6+2+7-5*3=how much.
6+2+7-5*3=多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">7 - 15</gadget>
<output>-8</output>

<gadget id="calculator">6 + 2 + (-8)</gadget>
<output>0</output>

<result>0</result>