Answer:
The length of the rectangular field is 12 ft and the width is 5 ft.
Explanation:
The area of a rectangle is:

The area of a rectangular field is, A = 60 ft.
The length of the field is:
l = w + 7
Compute the width of the field as follows:


Factorize the last equation by splitting the middle term as follows:

Now, since the width of rectangular field cannot be negative, the width is 5 ft.
Compute the length as follows:
l = w + 7
= 5 + 7
= 12
The length of the rectangular field is 12 ft.