Let the no. Of horses be x
9÷2 = 72÷x
X= 144÷9
No. Of horses = 16
        
                    
             
        
        
        
Since the angles add to 180°, angle F is 72°.
Using the law of sines,
DF/sin72° = 24/sin45°
x = 32.28
So, did you just guess at A?
This is just an answer from another website, but it should still work.
        
                    
             
        
        
        
(32°) = 1700 feet / x => x = 1700 feet / tan(32°) = 1700 feet / 0.625 = 2720 feet.