To solve the equation [tex]\( x - 12 = 9 \)[/tex], follow these steps:
1. Start with the given equation:
[tex]\[
x - 12 = 9
\][/tex]
2. To isolate [tex]\( x \)[/tex], you need to get rid of the [tex]\( -12 \)[/tex]. The easiest way to do this is by adding 12 to both sides of the equation. This step ensures that the equation remains balanced.
3. Add 12 to both sides of the equation:
[tex]\[
x - 12 + 12 = 9 + 12
\][/tex]
4. Simplify both sides:
[tex]\[
x = 21
\][/tex]
Therefore, the solution to the equation [tex]\( x - 12 = 9 \)[/tex] is [tex]\( x = 21 \)[/tex].
The correct answer is:
[tex]\[ \boxed{21} \][/tex]
