Answer: is A
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
Not only in mathematics, scientific proof also are required in the other field of science. Also maths proofs are of particular structure, containing steps and logics. So proving is like doing science, it is science. That's why it is important to prove. 
Step-by-step explanation:
 
        
                    
             
        
        
        
Regroup terms
Add 2x to both sides 
Simplify 4 - x + 2x to 4 + x
subtract 4 from both sides
subtract -6 - 4.
Answer: x = -10