Answer:
(b) 64 sq. in.
Explanation:
The shaded area is the difference between the overall area and the areas of the cutout corners.
The overall area is 10 in by 10 in, so is ...
A = s² = (10 in)² = 100 in²
The area of the cutout at each of the four corners is ...
A = s² = (3 in)² = 9 in²
So, the total area of the four cutouts is ...
cutout area = 4 × 9 in² = 36 in²
The remaining area is then ...
100 in² -36 in² = 64 in²