Answer:
(c) 18 ft
Step-by-step explanation:
If w is the width, then the length is (2w-12) and the perimeter is ...
P = 2(L +W)
84 = 2((2w -12) +w) = 2(3w -12)
42 = 3w -12 . . . . . divide by 2
54 = 3w . . . . . . . . add 12
18 = w . . . . . . . . . divide by 3
The width of the garden is 18 feet.
