How to do the Return calculation #$14$ on excel please

14. (Return calculation) On I January 2010, an American investor bought Sl worth of Swiss francs (SFr) and put it in a savings account for I year. The annual interest rate in Swiss francs was 6%. During that period, the interest rate in the United States was 2%. On the purchase date, the exchange rate was $1 = 1.56 SFr. a. One year after the start of the savings in Switzerland, the exchange rate was 1.45 Sfr per U.S. dollar. If the investor turned his savings back into dollars, what rate of return did he earn? b. What should be the exchange rate on I January 2011 in order for the investment in SFr to be better than the investment in the U.S. dollars?