A cuboid fuel tank (with a cover) has a length and width of 2.8 decimeters and a height of 3.5 decimeters. How many square decimeters of iron sheet is needed to make such a fuel tank?
一个长方体的油箱(有盖)，长和宽都是2.8分米，高是3.5分米，做一个这样的油箱至少要多少平方分米的铁皮？
<gadget id="calculator">2.8 * 2.8 * 2</gadget>
<output>15.68</output>

<gadget id="calculator">2.8 * 3.5 * 4</gadget>
<output>39.2</output>

<gadget id="calculator">15.68 + 39.2</gadget>
<output>54.88</output>

<result>54.88</result>