Answer: 384 ft^2 
Explanation:
Like it said set up a proportional equation and solve for dimensions in feets. 
The scale factor saids 0.75 in = 2 ft 
And the dimensions are 6 in by 9 in 
Now using the scale solve for how many feets will make 6 inches and how many feets will make 9 inches . 
 Solve by cross multiplying
 Solve by cross multiplying 
0.75x = 12 
x = 16 
 Cross multiply
 Cross multiply 
0.75x = 18 
x = 24 
Now since we know the new dimensions are 16ft by 24ft then we will multiply them together to find the area .
16 * 24 = 384 ft^2