The sum of the lengths of the sides of a cuboid is 84 cm, its length is 12 cm, its width is 7 cm, and its height is in cm.
一个长方体的棱长总和是84厘米，它的长是12厘米，宽是7厘米，高是多少厘米．
<gadget id="calculator">84 / 4</gadget>
<output>21</output>

<gadget id="calculator">12 + 7</gadget>
<output>19</output>

<gadget id="calculator">21 - 19</gadget>
<output>2</output>

<result>2</result>