(b) Dimensions of room = 10 m x 7 m x 5 m ∴ Area of walls = 2 x h ( l + b ) = 2 x 5(10+ 7) = 170 m2 Area covered by doors and windows = 2(1 x 3) + (2 x 1.5) + 2(1 x 1.5) = 6 + 3 + 3 = 12 m2 ∴ Area to be painted = (170 - 12) = 158 m2 ∵ Cost of painting =₹ 3 per m2 ∴ Total cost of painting the wall = 3 x 158 = ₹ 474