Answer:
432 square feet
Explanation:
The area of a trapezoid formula is:

when plugging in the numbers for the letters;
a = 20
b = 28
h = 18
then solve, the correct answer is 432.
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Another way to solve is to brank down the shape;
what is 28 - 20? its
8 * 18 / 2 = 72
18 * 20 = 360
100 + 360 = 432