A triangular billboard has a base length of 15 meters and a height of 5.4 meters. If this billboard is to be painted, 0.7 kilograms of paint is used per square meter. How many kilograms of paint should be used at least?
一块三角形的广告牌，底长15米，高5.4米，如果要油漆这块广告牌，每平方米用油漆0.7千克，至少要用多少千克油漆？
<gadget id="calculator">5.4 / 2</gadget>
<output>2.7</output>

<gadget id="calculator">15 * 2.7 * 0.7</gadget>
<output>28.35</output>

<result>28.35</result>