Answer:
width = 12cm
length = 36cm
Explanation:
let 'w' = width
let 'l' = length, which is 3w
since perimeter is twice the length plus twice the width we can write the following:
2w + 2(3w) = 96
2w + 6w = 96
8w = 96
w = 12
three times the width of 12 gives a length of 36
Check: 12 + 12 + 36 + 36 = 96
24 + 72 = 96
96 = 96