Answer:
144 in²
Explanation:
Find the area of the larger square, then subtract the area of the square we cut out.
The larger square has side length of 15, so it has an area of 15² = 225 in²
The smaller square has side length of 9, so it has an area of 9² = 81 in²
The area left over is
225 - 81 = 144 in²