Samra has decided to make flashcards to help her study for her Spanish exam. Each day she makes more flashcards to add to her collection. The number of flashcards she made on each of the first 4 days are shown in the table. She continues making flashcards according to this pattern for one month. 2 3 5 7 9 4 11 Day (n) Number of flashcards (an) a) Find a2 and describe its meaning in the context of this problem. b) Find S₁2 and describe its meaning in the context of this problem.