The answer would be C) The volume is the same in both cylinders
        
             
        
        
        
14+5x=3(-x+3)-11
14+5x=-3x+9-11
14+5x=-3x-2
add 2 to both sides
16+5x=-3x
subtract 5x from both sides 
16=-8x
divide both sides by -8
-2=x
Hope this helps! :)
 
        
             
        
        
        
Mental math is something that can be done i your head. 
for example you can do 1+1 in your head and you dont need a calculator or paper to do it so i would be called mental math
Hope this helps
remember if you ever need anything and you dont want to waste points you can just post it on my pfp or message me the question
        
                    
             
        
        
        
(-8)^2
(-8)(-8)
64
Hope this helps!