Let W = Width. Units are meters (m)

Let L = Length = W + 4

What do we know about the area of a rectangle.

A = L x W and A = 45 m^2. Therefore just substitute and solve.

45 = (W + 4)W

45 = W^2 + 4 W or

W^2 + 4 W - 45 = 0 Now factor or you us the quadratic formula.

(W + 9)(W - 5) = 0 so W + 9 = 0 or W - 5 = 0 =>

W = -9 or W = 5 the equation has 2 solutions but dimensions are only positive so we use W = 5

Therefore, W = 5m and L = W + 4 = 9m

Check: 9 x 5 = 45 correct.

Answer: W = 5m and L = 9m