Total parts:
3+2= 5
Half of perimeter (or the sum of the length and the width) is:
60 ft/2= 30 ft
Each part is:
30 ft/ 5 parts= 6 ft/part
The length costs 3 parts, and the length is:
6 ft/ 1 part* 3 parts= 18 ft.
The width costs 2 parts, and the width is:
6 ft/ 1 part* 2 parts= 12 ft.
The length and the width of the rectangle are 18 ft and 12 ft respectively~