For Halloween Katie and her sister combined the candy they received. Katie had 8 pieces of candy while her sister had 23. If they ate 8 pieces the first night, how many pieces do they have left?
<gadget id="calculator">8 + 23</gadget>
<output>31</output>

<gadget id="calculator">31 - 8</gadget>
<output>23</output>

<result>23</result>