C it reduces the amount of useful work done on objects move it up the ramp
 
        
             
        
        
        
D. It is personal in style.
        
                    
             
        
        
        
If the boat's speed is s, and the river's speed is r, and the boat is traveling east (0 degrees),
(0,r) + (s cos297,s sin297) = (6,0)
now just solve for r and s.
Pls mark me as brainliest