Answer:
length: 30 ft
width: 15 ft
Explanation:
The sum of length and width is half the perimeter, 45 ft.
The ratio of length to width is 2 : 1, so the sum in "ratio units" is 2+1 = 3. That is, each "ratio unit" stands for 45 ft/3 = 15 ft of actual length.
Jason's pool is ...
length : width = 2·15 ft : 1·15 ft = 30 ft : 15 ft
Jason's pool is 30 ft long and 15 ft wide.