To make a cuboid ventilation pipe with a length of 18 meters, a cross section with a length of 45 centimeters and a width of 30 centimeters, how many square meters of iron sheets are needed to make this ventilation pipe?
做一只长18米的长方体通风管，横截面长45厘米，宽30厘米，做这只通风管共需要铁皮多少平方米？
<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(9/20) * 18 * 2</gadget>
<output>81/5 = around 16.2</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 18 * 2</gadget>
<output>54/5 = around 10.8</output>

<gadget id="calculator">(81/5) + (54/5)</gadget>
<output>27</output>

<result>27</result>