Area of the entire grass field including the path = Length (85 + 5 +5) * Breadth (65 + 5+5)
= 95 * 75 = 7125 sq. m.
Area of the grass field excluding the path = 85 * 65 = 5525 sq. m.
So, area of the path = 7125 - 5525 = 1600 sq. m.
The cost of constructing is Rs. 5 per square meter.
So, the cost of constructing the entire path = 1600 * 5 = Rs. 8000