For a trapezoidal wheat field, the upper base is 3.9m, the lower base is 1.8m shorter than the upper base, and the height of the trapezoid is 2.5m. If the wheat harvested per square meter is 7.6kg, how many kilograms of wheat will be harvested in this wheat field?
一个梯形的小麦地，上底是3.9m，下底比上底短1.8m，梯形的高是2.5米，如果每平方米麦地收小麦7.6千克，那么这块麦地共收小麦多少千克？
<gadget id="calculator">3.9 - 1.8</gadget>
<output>2.1</output>

<gadget id="calculator">2.1 + 3.9</gadget>
<output>6</output>

<gadget id="calculator">2.5 / 2</gadget>
<output>1.25</output>

<gadget id="calculator">6 * 1.25 * 7.6</gadget>
<output>57</output>

<result>57</result>