For the given vectors  and
 and 
The dot product of vectors a and b is defined as = 
So, 

= -16+12
= -4
 
        
             
        
        
        
I think we need a coordinate grid for that,,
 
        
                    
             
        
        
        
3x-13=2
move -13 to the other side
sign changes from -13 to +13
3x-13+13=2+13
3x=2+13
3x=15
divide both sides by 3 to get x by itself
3x/3=15/3
cross out 3 and 3, divide by 3 and then becomes 1*1*x=x
x=15/3
x=5
answer:
x=5
 
        
             
        
        
        
I don’t see the problems you want me to solve. Sorry
        
             
        
        
        
4 units right and 4 units down