40 feet by 4 feet
Given length (l) = 100 feet
width (w) = 10 feet
As mentioned in the question the size of garden is decreased to 2/5 of its size. It will effect the length and width with the same proportion.
So,
New length = 100 * 2/5 = 40 feet
New width = 10 * 2/5 = 4 feet
Therefore, the scale of new drawing would be 40 feet by 4 feet
