Answer is 264 
You just multiply at three numbers
        
             
        
        
        
Answer: B. Every 10th students that enters the cafeteria
Explanation:
B is a random sample, while A, C, and D are biased.
        
             
        
        
        
Answer: -3/5
Step-by-step explanation:
 
        
             
        
        
        
Sin 2 x + 2 sin x = 0
2 sin x cos x + 2 sin x = 0 / : 2
sin x cos x + sin x = 0
sin x ( cos x + 1 ) = 0
sin x = 0,  cos x + 1 = 0,  cos x = - 1;
Answer:
x = 0,  or x = π