Ratio in length and breadth = 5 : 4
Area of rectangular field = 3380 m^{2}
Let length = 5x and breadth = 4x
5x x 4x = 3380
=> 20x^{2} = 3380
x^{2} = 3380/20 = 169 = (13)^{2}
x = 13
Length = 13 x 5 = 65 m
Breadth =13 x 4 = 52 m
Perimeter = (l + b) = 2 x (65 + 52) m = 2 x 117 = 234 m
Rate of fencing = ₹ 75 per m
Total cost = 234 x 75 = ₹ 17550