Calculation: 997+3-(997-3)=how much.
计算：997+3-(997-3)=多少．
<gadget id="calculator">997 - 3</gadget>
<output>994</output>

<gadget id="calculator">3 - 994</gadget>
<output>-991</output>

<gadget id="calculator">997 + (-991)</gadget>
<output>6</output>

<result>6</result>