Area of the square plot = (25 m)^{2 }= 625 m^{2 }Area of the house = (15 m) × (20 m) =300 m^{2}

Area of the remaining portion = Area of square plot − Area of the house = 625 m^{2 }− 300 m^{2} = 325 m^{2}

The cost of developing the garden around the house is Rs 55 per m^{2}. Total cost of developing the garden of area 325 m^{2} = Rs (55 × 325) = Rs 17,875