Answer:

Explanation:
Let d be the number of days.
We have been that each day Katie finds 12 more seashells on beach, so after collecting shells for d days Katie will have 12d shells.
We are also told that Katie already has 34 seashells in her collection, so total number of shells in Katie collection after d days will be:

As Katie wants to collect over 100 seashells, so the total number of shells collected in d days will be greater than 100.