Answer:
29
Explanation:
P = 2*length + 2*width
P = 115
length = 28.5
width = ?
2*28.5 + 2*width = 115
2* width = 115 - (2*28.5)
2* width = 115 - 57
2* width = 58
width = 58 / 2 = 29
(checking by plugging in 29 as width and 28.5 as length into the formula)