Solution - Linear equations with one unknown

Rearrange:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :

                     12-(n-9)=0 

Step by step solution :

Step  1  :

Solving a Single Variable Equation :

 1.1      Solve  :    -n+21 = 0 

 Subtract  21  from both sides of the equation : 
                      -n = -21
Multiply both sides of the equation by (-1) :  n = 21

One solution was found :