which equation can be used to find the answer? a garden with four sides has a perimeter of 45 ft. three of the sides have lengths of 7 ft, 14 ft, and 13 ft. what is the length of the fourth side? a. s – 7 – 14 – 13 = 45 s = 79 79 ft b. s – 45 = 7 14 – 13 s = 53 53 ft c. s – 7 14 13 = 45 s = 25 25 ft d. s 7 14 13 = 45 s = 11 11 ft