Let height of room be h m
Area of four walls = 2h(7+5)m2 = 24m2
Area of walls without doors and windows(as doors and windows cannot be painted) = 24h-(2x1.5 + 2x1.5x1)m2
(24h-6) x12.50 = 825
or, 24h - 6 = 825/12.50 = 66
or, 24h = 72
or, h = 3
Answer: - Height of room is 3m.