A parking lot that is 3 feet longer than it is wide has an area of 550 square feet. How many feet long is the parking lot?

Let W=width of parking lot,

then Length = W+3

Total area = W (W+3) = 550

Exapand and express in standard quadratic form

W^2+3x-550=0

Factor

(W+25) (W-22) = 0

Therefore W=22 or W=-25, reject negative root, so

Width = 22'

Length=22+3=25'

Check: (area = 22' * 25'=550 sq. ft, ok)