let
y----------> the length of the rectangle
x---------> the width of the rectangle
P--------> perimeter of a rectangle
we know that
P=38 ft
[P]=2*[x+y]------> 38=2*[x+y]------> equation 1
y=5+x-------> equation 2
substitute 2 in 1
P=2*[x+(5+x)]---------> P=4x+10---------> the given equation
4x=38-10--------> 4x=28----> x=7 ft
y=5+7-----> y=5+7------> y=12 ft
the answer is
the width is 7 ft