The school plans to make some triangular placards recently. The bottom of each placard is 8 decimeters and the height is 6.5 decimeters. How much material is needed to make 15 such placards?
学校近期准备做一些三角形的标语牌，每块标语牌的底是8分米，高是6.5分米．做15块这样的标语牌，需要多少材料？
<gadget id="calculator">6.5 / 2</gadget>
<output>3.25</output>

<gadget id="calculator">8 * 3.25 * 15</gadget>
<output>390</output>

<result>390</result>