please help me understand this

Score: 0 of 1 pt 16 of 16 (8 complete) HW Score: 40.63%, 6.5 of 16 pts P4-32 (similar to) Question Help Challenge problem. Each holiday season, Michael received a U.S. savings bond from his grandmother. Michael eventually received twelve savings bonds as shown in the following table: The bonds vary in their rates of interest and their face values. Assume today is December 31, 2011. What is the value of this portfolio of U.S. savings bonds? On what date does each of the individual bonds reach its face value or maturity date (note that the price is half the face value)? Estimate to the nearest month and year for each bond. Note: The bonds continue earning interest past their maturity dates. What is the current value of the bond that was issued on 12 / 31 / 1990? $ (Round to the nearest cent.)