Total surface area of the room=2(lh+lb+hb)m2=2[9×6.5+9×8+8×6.5]m2=365m2Area of the door =l×b=2×1.5=3m2Area of the windows=l×b=1.5×1=1.5m2∴ Surface area of walls=TSA of room −Area of door−Area of windows=365−3−1.5=360.5m2Cost of whitewashing per square meter=Rs. 6.40∴ Cost of whitewashing the walls=Rs. 6.40×360.5=Rs. 2307.2.