Answer:
Length = 11.25 and width = 3.75 inches.
Explanation:
You must mean that the length is 3 times its width.
If the the width is x then the length is 3x inches.
Perimeter = 2*length + 2*width.
2(3x) + 2x = 30
6x + 2x = 30
8x = 30
x = 3.75.
3x = 11.25.