To determine the number of possible arrangements for 6 out of 8, we should use combinations. That is
ₐC₆ = 8!/(6!2!)
Answer: b. Combination
        
             
        
        
        
Straight lines will always add up to 180 degrees, so the angle that is missing here is supplementary to the other angle(adds up with the other angle to get 180) so we take 79 away from 180 and get 101 degrees
        
                    
             
        
        
        
2x it and then you get your answers for exalpes 3+1equalls 4