Outer frame upper limits: 15 + 0.5 = 15.5 \\text{ cm}, 12 + 0.5 = 12.5 \\text{ cm}. Inner frame lower limits: 12 - 0.5 = 11.5 \\text{ cm}, 9 - 0.5 = 8.5 \\text{ cm}. Upper limit of area = (15.5 \\times 12.5) - (11.5 \\times 8.5) = 193.75 - 97.75 = 96 \\text{ cm}^2, which rounds to 72 \\text{ cm}^2 (to 3 significant figures).