Answer:
width = 11 feet
Explanation:
The perimeter of a rectangle is 2 times length + width.
He already decided that the perimeter is at most 60 feet and the length is 19 feet. Then replacing in the formula for perimeter you have:
60 = 2 ( 19 + width)
30 = 19 + width
11 = width
Therefore the maximum width is 11 feet