What does it means “Deleting all user's homework”?

How can you repin an image on your pinterest pin board a. click on the "repin" button b. click on the "add pin" button c. click on the "upload a pin" button d. click on the "save pin" button.

Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?

The processing of data in a computer involves the interplay between its various hardware components.