Students of a school staged a rally for cleanliness campaign. They walked through the lanes in two groups. One group walked through the lanes AB, BC and CA while the other through AC, CD and DA (See Fig.
). Then they cleaned the area enclosed within their lanes. If AB = 9 m, BC = 40 m, CD = 15 m, DA = 28 m and `/_B = 90^@`, which group cleaned more area and by how much ? Find the total area cleaned by the students.