**L= 4 + W**

Area is 45, so

L times W = 45

substituting the value of L, we get (4+W)*W=45, after simplifying this we get

**4W+W**

^{2}=45**W**this is a quadratic equation and after solving this we get the factors 9 and -5

^{2}+4W-45=0,( W+9) and (W-5) = 0

after solving for W we get W=-9 or W=5, since width cannot be negative, so

**width = 5**Now substituting the value of W=5 in L = 4 +5, we get

**length = 9**_{}