The cross-section of a 350-meter-long barrage is trapezoidal. Its upper base is 13 meters long, its lower base is 44 meters long, and its height is 4 meters. How much earth and rocks are needed to build this barrage?
一条350米长的拦河大坝的横截面是梯形，它的上底长13米，下底长是44米，高是4米，修这条拦河坝，一共需要土石多少方？
<gadget id="calculator">13 + 44</gadget>
<output>57</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">57 * 2 * 350</gadget>
<output>39_900</output>

<result>39_900</result>