79-(46-21+54)=how many.
79-(46-21+54)=多少．
<gadget id="calculator">46 - 21</gadget>
<output>25</output>

<gadget id="calculator">25 + 54</gadget>
<output>79</output>

<gadget id="calculator">79 - 79</gadget>
<output>0</output>

<result>0</result>