trapezoid has an area of 12.6㎡, a height of 3m, and a lower base twice that of the upper base. What is the upper base in m?
一个梯形，面积是12.6㎡，高是3m，下底是上底的2倍，上底为多少m．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12.6 * (2/3) * (1/3)</gadget>
<output>2.8</output>

<result>2.8</result>