Answer:
The wide of the walkway is 5ft.
Step-by-step explanation:
In first place you have a rectangular garden of 30ft by 40 ft as shown in Figure 1 (Added file).
So, the area of this rectangle is:
Area=1200ft
Now, the new garden has a walkway of uniform width around it, and the area of the new rectangle is one-half the area of the old garden
In order to be a walkway of uniform width it's necessary to substract of each side the same amount, for this case will be 5 ft, as shown in the Figure 2. Now the new rectangule is 20ft by 30ft.
Which is exactly one-half the area of the old garden.
This means the width of the walkway is 5ft.
