A trapezoidal propaganda wall has an upper base of 8 meters, a lower base of 10 meters, and a height of 6 meters. The wall is painted with 810 kilograms of cement. How many kilograms of cement is used on average per square meter?
一块梯形宣传墙，上底是8米，下底是10米，高是6米，用810千克的水泥粉刷了这面墙，平均每平方米用水泥多少千克？
<gadget id="calculator">8 + 10</gadget>
<output>18</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">18 * 3</gadget>
<output>54</output>

<gadget id="calculator">810 / 54</gadget>
<output>15</output>

<result>15</result>