[tex] perimeter \ of \ square : \ P= 160 \ m \\\\ P=4a \\\\4a =160 \ \ | \ divide \ both \ sides\ by\ 4 \\\\ a= 40 \ m \\\\Area \ of \ square : \\ \\A=a^2 \\ \\A=40^2=1600 \ m^2 \\\\Answer : \ The \ area \ of \ this \ garden \ it \ 1600 \ m^2 . [/tex]