Answer:
The answer is: At least 80%
Step-by-step explanation:
If corporations want to file consolidated tax returns they must be part of an affiliated group. They will be part of the same affiliated group if at least 80% of the voting power and stock value of each is owned by a mutual "parent corporation" and by each other corporation of the affiliated group.
In this case, Dana Corp. must own 80% the stocks and voting power of Seco Corp.