I don't exactly get what your supposed to do but I thought it like this:
T V
3000 0
3000 4000
5000 4000
5000 8000
the last two are the final answers on how long the ran or it could be Terrel ran 5 kilometers while Victor ran 8 kilometers, but still idk what exactly your supposed to put
        
             
        
        
        
7x - 5y = 21....(4,?)...so sub in 4 for x and solve for y
7(4) - 5y = 21
28 - 5y = 21
-5y = 21 - 28
-5y = - 7
y = 7/5
check..
7(4) - 5(7/5) = 21
28 - 35/5 = 21
28 - 7 = 21
21 = 21 (correct)
the other coordinate is 7/5......(4,7/5)
        
             
        
        
        
I would say that there are 29 boys in the class.
        
                    
             
        
        
        
(32°) = 1700 feet / x => x = 1700 feet / tan(32°) = 1700 feet / 0.625 = 2720 feet.