The area of a trapezoid is 6.8 square meters, the height is 1.6 meters, and the length of the upper base is 3.1 meters. What is the length of the lower base of the trapezoid?
一个梯形的面积是6.8平方米，高是1.6米，上底长是3.1米，则这个梯形的下底长是多少米
<gadget id="calculator">6.8 / 1.6</gadget>
<output>4.25</output>

<gadget id="calculator">4.25 * 2</gadget>
<output>8.5</output>

<gadget id="calculator">8.5 - 3.1</gadget>
<output>5.4</output>

<result>5.4</result>