Answer:
The 12 ( after 28) should be 14.
This 12 does not belong to the series.
Explanation:
After every 2 numbers, 2 is added to the last number, so we have 100-50 + 2 = 52 - 26, and the second of the paired numbers is 1/2 of the first.
So after 28 the numbers should be 14 - 16 - 8 - 10. The 12 does not belong.