First, we need to get the total area of the rectangular pool.
Area = l * w
Area = 20 ft * 50 ft
Area = 1000 ft^2
Then the deck is 456 ft^2 with the width of 20ft, the same as the rectangular pool.
Area = l * w
456 = l * 20
l = 456 / 20
l = 22.8 ft.
So the walkway is 22.8ft wide.