At first the area is x^{2} by trimming 4 inches off each of 4 edges, the new area is (x-8)^{2}. then another 4 inches off leaves the area =A = (x-16)^{2} = x^{2}-32x+256 square inches

The area removed in the first trim job was 4x twice + 2(x-8)(4) = 8x+8x-64=16x-64 square inches

check that by finding the area of what's left, then add what was removed, and the sum should be the original area A=x^{2} The area left after the first trim is (x-8)^{2}=x^{2}-16x+64. It's now an x-8 by x-8 square.

The area left after the 2nd trimming is (x-16)^{2}=x^{2}-32x+256. So the area removed in two trimmings was 32x-256. Those two sum to the original x^{2} total area removed minus area removed in 1st trim = area removed in 2nd trim. 32x-256 minus 16x-64 = 16x-192

The area removed in the 2nd trimming was 4(x-8) twice + 2(x-16)(4) = 8x-64 +8x-128 = 16x-192 square inches