The area of a trapezoid is 10 square meters, the upper base is 3 meters, and the height is 2.5 meters. What is the length of the lower base?
一个梯形的面积为10平方米，上底为3米，高为2.5米，求下底长多少？
<gadget id="calculator">8 - 4</gadget>
<output>4</output>

<result>4</result>