A cuboid glass tank is 6 decimeters long, 5 decimeters wide and 3 decimeters high, and the water depth inside is 2.8 decimeters. How many liters of water in the tank will overflow if a cube of iron with a side length of 3 decimeters is thrown in?
一只长方体的玻璃缸，长6分米、宽5分米、高3分米，里面的水深2.8分米．如果投入一块棱长为3分米的正方体铁块，缸里的水将溢出多少升？
<gadget id="calculator">5 * 6 * 2.8</gadget>
<output>84</output>

<gadget id="calculator">3 * 3 * 3</gadget>
<output>27</output>

<gadget id="calculator">6 * 5 * 3</gadget>
<output>90</output>

<gadget id="calculator">27 - 90</gadget>
<output>-63</output>

<gadget id="calculator">84 + (-63)</gadget>
<output>21</output>

<result>21</result>