Boomer Co$.$ offers a financial security that pays $$200$ annually for $5$ years and the market rate is $5\%.$ Explain how to calculate using finance calculator $($BA II$)$ and what to enter to get results and include the ANSWER to each question please.

a$.$ How much is that security worth to you today?

b$.$ How much is the security worth if the market rate is $5\%$ for the first three years, then decreases to $3\%$ for the final two years of payments?

C$.$ How much is the security worth if the $$200$ payment grows by $4\%$ every year?