Answer:
90 cm²
Explanation:
You want the area of a figure that can be described as a 12 cm by 9 cm rectangle with a 6 cm by 3 cm rectangle removed from it.
Area
You can figure the area of this a number of ways. One is to look at the rectangle that bounds it, and subtract the portions of that rectangle that are not included in the figure.
Here, the shaded area is the difference between the "bounding" 12 × 9 cm rectangle area and the "missing" 6 × 3 cm rectangle area:
Area = (12 cm)(9 cm) -(6 cm)(3 cm) = 108 cm² - 18 cm² = 90 cm²
The area of the figure is 90 cm²
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Additional comment
Lines have been drawn that divide the figure into three smaller shapes: a rectangle that is 12 cm by 6 cm, and two squares that are 3 cm by 3 cm.
The shaded area is the total of these:
(12 cm)(6 cm) + 2(3 cm)(3 cm) = 72 cm² +2(9 cm²) = (72 +18) cm² = 90 cm²
The area should be (and is) the same, regardless of how you compute it.
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