he width is 5 feet and the length 10 feet
Let the width of the garden = W
Therefore the length = W + 5
The two sidewalks alongside the length are therefore W + 5 feet long by 2 feet wide = 2(W + 5) square feet each
The 2 sidewalks alongside the width = W feet long by 2 feet wide = 2W square feet each
In addition there are the 4 corners which are each 2 feet by 2 feet = 4 square feet each
Area of sidewalk is therefore
2 * lengths = 2 * 2(W + 5) = 4W + 20
2 * widths = 2 * 2W = 4W
4 corners = 4 * 4 = 16 square feet
But we are told that the area = 76 square feet
Therefore 4W + 20 + 4W + 16 = 76
8W + 36 = 76
8W = 40
W = 5
Therefore as the width is five feet the length is 5 + 5 = 10 feet