Inside a square garden of side 158 m ,a road 4 m width wide is built all around . what is the area of the remaining part of the garden

Area of big square=side*side
                                158*158
                             =24964 m2
length of small square=158-(4+4)
                               =150 m
area of small square=150*150
                               = 22500 m2
​area of remaining part=outer area-inner area
                                 =24964-22500
                                   2464 m2