No one is going to do all this for 5 points...
        
                    
             
        
        
        
First part  its 4C2  = 4*3 / 2 = 6
Second part
12 * 100
----------    =   4.3 %
   280
        
                    
             
        
        
        
3.) 5x-6=0, Add 6 to either side -> 5x=6, divide each side by 5 -> x=6/5 ---- 4.) x+y/3=5, multiple each side by 3 -> x+y=15, move y to the other side -> x=-y+15
        
                    
             
        
        
        
Polynomials can have double roots, in fact they're pretty common. if you get a reasonable zero it costs very little time to try it again for a double root. answer is the second choice