【Question 4】
The upper base, height, and lower base of a trapezoid form an arithmetic sequence, where the height is 12. What is the area of the trapezoid? $\qquad$.


【Analysis and Solution】
Since the upper base, height, and lower base of the trapezoid form an arithmetic sequence;
Therefore, upper base + lower base $=$ height $\times 2=12 \times 2=24$;
The area of the trapezoid $=($ upper base + lower base $) \times$ height $\div 2=24 \times 12 \div 2=144$.