Answer:
398 ft²
Step-by-step explanation:
Assuming you have correctly described the total area in terms of non-overlapping triangles and a rectangle, you can put the dimensions into the appropriate area formula and add up the pieces.
Triangle area = 1/2·bh
Rectangle area = bh
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So, the first triangle has an area of ...
1/2·(20 ft)(20 ft) = 200 ft²
The second triangle has an area of ...
1/2·(6 ft)(6 ft) = 18 ft²
The rectangle has an area of ...
(30 ft)(6 ft) = 180 ft²
And the area total is ...
200 ft² +18 ft² +180 ft² = 398 ft²