sequences and series - Consecutive Odd Numbers?

When doing some exercises on Khan Academy, the following question came up: "The sum of 3 consecutive odd numbers is 69.
What is the third number in this sequence?" My answer was 27 because I thought -Odd- Numbers to show up as = 1, 3, 5, 7, etc. Apparently, it consists of x, 2, 4, 6, etc. Can someone explain this to me?

• English is not my first or second language in case I'm missing something..

KhanAcademy's Explanation

Answer

Consecutive odd numbers differs $2$.

Now suppose $a$ is a odd numbers, then $a-2, a+2$ are also odd numbers.

Now it is given that $$a-2+a+a+2=69\\\Rightarrow 3a=69\\\Rightarrow a=23$$

Then the third number in this sequence is $a+2=25$ (Ans.)