A trapezoid with an area of 20 square decimeters, when the upper base is 12 decimeters and the lower base is 8 decimeters, what is the height?
一个面积是20平方分米的梯形，当上底是12分米，下底是8分米时，高是多少．
<gadget id="calculator">12 + 8</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">20 * (1/10)</gadget>
<output>2</output>

<result>2</result>