To get Second Number add $3$ to first number and to get third number subtract $2$ from second number and this process will continue.
Hence,$10$ is the Answer.
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 $10$
given series having the following patterns:
So the next term should be $10.$