The cross-section of a small ditch is trapezoidal, the width of the upper base is 22dm, the width of the lower base is 15dm, and the depth of the ditch is 6dm. Find the cross-sectional area of the ditch.
一条小渠的横截面是梯形，上底宽22dm，下底宽15dm，渠深6dm，求水渠的横截面面积．
<gadget id="calculator">22 + 15</gadget>
<output>37</output>

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

<gadget id="calculator">37 * 3</gadget>
<output>111</output>

<result>111</result>