To make two identical cuboid buckets (without lids), the length and width are 3 decimeters, and the height is 5 decimeters. How many square decimeters of iron sheets are needed at least?
要做两只一样的长方体的水桶(无盖)，长和宽都是3分米，高5分米，至少需要铁皮多少平方分米？
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">3 * 5 * 4</gadget>
<output>60</output>

<gadget id="calculator">9 + 60</gadget>
<output>69</output>

<gadget id="calculator">69 * 2</gadget>
<output>138</output>

<result>138</result>