If the area of a trapezoid is 180 square decimeters and the height is 20 decimeters, what is the sum of the upper and lower bases?
一个梯形的面积是180平方分米，高是20分米，那么上、下底之和是多少分米．
<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">180 * (1/10)</gadget>
<output>18</output>

<result>18</result>