Select the equation needed to solve the following word problem:

Kayla is sending invitations to 20 of her friends for a pizza party. If there are 12 invitations left to send out, how many invitations has she already mailed?

A. [tex]x + 12 = 20[/tex]
B. [tex]x + 20 = 12[/tex]
C. [tex]x + 8 = 12[/tex]
D. [tex]x - 8 = 20[/tex]

To solve the problem, let's break it down step-by-step:

1. Understand the Problem:
- Kayla is sending invitations to a total of 20 friends.
- There are 12 invitations left to send.

2. Determine What We Need to Find:
- We need to find out how many invitations she has already mailed.

3. Set Up an Equation:
- Let's use [tex]\( x \)[/tex] to represent the number of invitations Kayla has already mailed.
- Since she has sent a certain number of invitations and has 12 left, the total combined must equal 20.
- Therefore, the equation we can set up is: [tex]\( x + 12 = 20 \)[/tex].

4. Solve the Equation:
- To find [tex]\( x \)[/tex], we can subtract 12 from both sides of the equation:
[tex]\[
x + 12 = 20 \\
x = 20 - 12 \\
x = 8
\][/tex]

5. Conclusion:
- Kayla has already mailed 8 invitations.
- The correct choice that reflects this situation is A. [tex]\( x + 12 = 20 \)[/tex].

This step-by-step approach helps verify that the correct equation to solve the problem is indeed A: [tex]\( x + 12 = 20 \)[/tex].