Hi. To solve this problem, we break it down like this:
P = 2L + 2W < 52
Set it equally
L + W = 26 (because 1/2 of 52 is 26)
(W + 3) + W = 26
2W = 23
W = 11 1/2
L = W + 3 = 14 1/2
So the final dimensions are: Width = 11 1/2 and the Length is 14 1/2
I hope this helps.
Take care,
Diana
