Please help! Im not sure! If y + 1= 2015, for what positive integer w will 2y^2 + 2y = 2015w?

Write an explicit formula that represents the sequence defined by the following recursive formula:

Ateacher has $80 to buy workbooks. each work book cost $3. if she buys as many workbooks as possible, how much money does she have leftover? a) $2 b) $4 c) $6 d) $8

What are the triple angle formulas? is it related to double angle identities?