Please show all work (use of formula, etc)

You have just joined the investment banking firm of Danny, Chatman, and Howard. They have offered you two different salary arrangements. You can have $80,000 per year for the next two years, OR you can have $70,000 per year for the next two years, along with a $15,000 signing bonus today. The bonus is paid immediately, and the salary Is paid at the end of each year. If the market interest is 6 percent, which do you prefer? (numerical proof)