To solve the equation $x - 3 = 9$, follow these steps:

1. Add 3 to both sides of the equation to isolate $x$:

$x - 3 + 3 = 9 + 3$

2. Simplify:

$x = 12$

Thus, the solution is $x = 12$.

Would you like any further explanation, or do you have any questions?

Related questions:

1. What is the process to solve an equation with variables on both sides?
2. How do you solve an equation with parentheses, like $2(x - 3) = 10$?
3. How do you solve a system of linear equations with two variables?
4. What is the method for solving quadratic equations?
5. How do you check if a solution to an equation is correct?

Tip: Always check your solution by plugging it back into the original equation.