Answer: d) 12 ft
Step-by-step explanation:
Let x be the width of the room , the the length of the room will be 2x.
We consider the shape of room is rectangle.
We know that the area of rectangle is given by :-
, where l is length and w is width.
Given : Area of the room is 288 square feet

Since, width cannot be negative, so the width of the room = 12 feet.