In the given series having 2 different series such as $7,8,9,10,…., 10,11,12,$. In the odd place, we put the first series term, even place we put the second series term. so the next term of the series should be $10$
Another way,
given series having the following patterns:
- $7+3=10$
- $10-2=8$
- $8+3=11$
- $11-2=9$
- $9+3=12$
- $12-2=10$
So the next term should be $10.$