The sum of the upper and lower bases of the trapezoid is 36 decimeters and the height is 15 decimeters. What is its area?
梯形的上、下底之和是36平方分米，高是15分米，它的面积是多少平方分米．
<gadget id="calculator">15 / 2</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">36 * (15/2)</gadget>
<output>270</output>

<result>270</result>