Length of the wall = 4 m = 400 cm
Breadth of the wall = 3 m = 300 cm
Area of the wall = (400×300) cm2 = 120000 cm2
Length of the tile = 12 cm
Breadth of the tile = 10 cm
Area of one tile = (12×10) cm2 = (120) cm2
Cost of 1 tile = Rs 22.50
Cost of 1000 tiles = (1000 × 22.50) = Rs 22500
Thus, the total cost of the tiles is Rs 22500.