pls tell me why and show me the detail, thank you

Mary's Financial Investments 1. Mary bought a five-year $10,000 Guaranteed Income Certificate (GIC) on January 1, 2014 (for which she paid If Mary can reinvest the $10,000). interest income from the GIC at 10% each year, what will 2. The GIC pays $1,000 in interest income be the present worth (to the each year on December 31,2014 to nearest dollar) of the $10,000 December 31,2018 giving Mary a 10\% investment in actual dollars rate of return on her investment. on January 1, 2014? 3. On December 31,2018 (the GIC's maturity date), Mary will receive, in addition to her last interest payment of $16,672; $1,000, the full amount of $10,000 that she invested on January 1,2014. b. $10,000; c. $11,513; 4. During this period, the annual inflation d. $0 rate is expected to be 5 percent. Ans.$10,000[(1.1)5/(1.1)5]=$10,000