Answer:
72 cm²
Explanation:
The shaded area is 1/4 of the rectangle, so the unshaded area is 3/4 of the rectangle--3 times the area that is shaded.
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Unshaded area = 3 × 24 cm² = 72 cm²
The region that is not shaded has an area of 72 cm².
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You can mark the midpoint of MR as point S, and draw segment PS. That will divide the rectangle into 4 congruent triangles, one of which is shaded. The congruent triangles all have the same area, so the shaded area is 1/4 of the total area, and the unshaded area is 3 times the shaded area.