The upper base of a trapezoid is enlarged to 3 times the original size, the lower base is enlarged to 3 times the original size, the height remains the same, and the area is enlarged to how many times the original size
一个梯形的上底扩大为原来的3倍，下底扩大为原来的3倍，高不变，面积扩大为原来的多少倍
<result>3</result>