Question 857894
Rarely does a teacher ask a question where the sides of a rectangle come out to decimals.
L * W = Area
Typically the sides would be the factors of 30.
30,1
15,2
10,3
6,5
None of those fit with the  L = W+4 information.  Would you double-check your posting?
Otherwise, what we have is:
L * W = 30
L = W + 4
(W + 4) * W = 30
W^2 + 4W = 30
W≈3.830951894845
.
Can you see why I think one of the question's numbers must be wrong? :-)