Rahul is fond of colourful fish. So his mother wants to make an aquaríum for him at their home. It is in the form of a cuboid whose external measures are 80 cm x 30 cm x 40 cm. Rahul wants to cover the base, side faces and back face with coloured papers. Find the area of the coloured paper needed. If cost of 1 square cm. of paper is 2.50 Rs., then find the total cost ?