Let , side lawn is a.
Area of boundary is :
[tex]A=4\times5\times a\\\\A=20a\ m^2[/tex]
Now, total cost is given by :
[tex]T=20a\times 36.25\\\\90625=725a\\\\a=125\ m[/tex]
Area left is :
[tex]A'=a^2-20a\\\\A'=125^2-20\times 125\ m^2\\\\A'=13125\ m^2[/tex]
Price to empty space with turfs is :
[tex]P=A'\times 20\\\\P=13125\times 20\\\\P=262500[/tex]
Therefore, the cost of covering the empty space with turfs at the rate of Rs 20 per sq. metre is Rs 262500.
Hence, this is the required solution.
