Answer: what wrong
 
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
Answer D:  12
Step-by-step explanation:
Three distinct denominators are shown here:  4, 3 and 2.  The LCD is 12.
This corresponds to answer D.
 
        
             
        
        
        
B .....,,,..,....,,..,,..,..
        
             
        
        
        
The two equations are 

and

the first equation can be solved for x to be 

next you can substitute x in the second equation

Distribute 4 to everything in the parentheses

combine like terms:

subtract 28 from both sides of the equation

divide both sides by -1.5

plug this in to the original equation of x+y=7

subtract 4 from both sides.

Final Answer: they bought 3 adult tickets and 4 student tickets
Hope this helps!