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