A piece of trapezoidal land is all planted with corn. The upper base of this land is 28.7m, the lower base is 31.3m, and the height is 15.5m. If 1.8 kg of corn is produced per square meter, how many dry grams of corn can this field produce?
一块梯形土地全部种玉米，量得这块地的上底为28.7m，下底为31.3m，高是15.5m．如果每平方米产玉米1.8kg，这块地可以产玉米多少干克？
<gadget id="calculator">28.7 + 31.3</gadget>
<output>60</output>

<gadget id="calculator">15.5 / 2</gadget>
<output>7.75</output>

<gadget id="calculator">60 * 7.75 * 1.8</gadget>
<output>837</output>

<result>837</result>