He answered 8 questions incorrectly. 2*8=16 100-16=84
        
                    
             
        
        
        
First you have to find the angle B (check attachment)

Then you can find the last angle inside the triangle, which I'll call C

Now you can find angle A

 
        
             
        
        
        
PEMDAS (order of operations rules) require that we perform operations in a certain order: anything inside parentheses first, followed by any exponentiation, followed by mult. and div., finally followed by addition and subtraction.
Thus, we must evaluate 5+8÷4-1 first, as it's inside parentheses. Focusing on the division first, we get 5+8÷4-1 = 5 + 2 - 1, or 6.
Then we have 5 - [6], which comes out to -1.
 
        
                    
             
        
        
        
8: slope is 1/2 and y intercept is 0
9: slope is 7/4 and y-intercept is 0