The pattern alternates between adding 3 and subtracting 2.
- 07 + 3 = 10 - 10 - 2 = 08 - 08 + 3 = 11 - 11 - 2 = 09 - 09 + 3 = 12 - 12 - 2 = 10 (so the next number in the sequence is 13).
Thus, the next number in the series is 13.
The correct answer is "13."
Which of the following is correct? 
Look at this series:
U32, V29, ____, X23, Y20, ....
What number should fill the blank?