Seems easy but is not

These math problems are more fun when you find yourself trying to remember the math you learned as a child. Can you figure out the correct solution? At the top of the picture, we see the task and then four possible answers.

Which solution do you think is the correct one? How did you come up with it? Take your time and think about it to find the correct solution. Done? Below you can check if you picked the right number!

The correct answer is B: 12.
Why is 12 the correct answer?
Well, if you remember from your school days, according to the order of operations, you do multiplication before addition and subtraction, so you start by solving 3 x 3, which results in 9.
Then we are left with a simpler math problem: 3 + 9 – 3 + 3
The answer is therefore 12.